Method and apparatus for controlling medical fluid pressure

ABSTRACT

A method, system and apparatus for performing peritoneal dialysis are provided. To this end, in part, a method of controlling pressure in a medical fluid pump is provided. The method includes the steps of controlling a pump member acceleration during a first portion of a pump stroke and adaptively changing the pump member velocity during a second portion of the pump stroke.

BACKGROUND OF THE INVENTION

[0001] The present invention generally relates to dialysis systems. Morespecifically, the present invention relates to automated peritonealdialysis systems. The present invention also relates to methods ofperforming automated peritoneal dialysis and devices for performingsame.

[0002] Due to disease, insult or other causes, a person's renal systemcan fail. In renal failure of any cause, there are several physiologicalderangements. The balance of water, minerals and the excretion of dailymetabolic load is no longer possible in renal failure. During renalfailure, toxic end products of nitrogen metabolism (urea, creatinine,uric acid, and others) can accumulate in blood and tissues.

[0003] Kidney failure and reduced kidney function have been treated withdialysis. Dialysis removes waste, toxins and excess water from the bodythat would otherwise have been removed by normal functioning kidneys.Dialysis treatment for replacement of kidney functions is critical tomany people because the treatment is life saving. One who has failedkidneys could not continue to live without replacing at least thefiltration functions of the kidneys.

[0004] Hemodialysis and peritoneal dialysis are two types of dialysistherapies commonly used to treat loss of kidney function. Hemodialysistreatment utilizes the patient's blood to remove waste, toxins andexcess water from the patient. The patient is connected to ahemodialysis machine and the patient's blood is pumped through themachine. Catheters are inserted into the patient's veins and arteries toconnect the blood flow to and from the hemodialysis machine. As bloodpasses through a dialyzer in the hemodialysis machine, the dialyzerremoves the waste, toxins and excess water from the patient's blood andreturns the blood back to the patient. A large amount of dialysate, forexample about 120 liters, is used to dialyze the blood during a singlehemodialysis therapy. The spent dialysate is then discarded.Hemodialysis treatment lasts several hours and is generally performed ina treatment center about three or four times per week.

[0005] Peritoneal dialysis utilizes a dialysis solution or “dialysate”,which is infused into a patient's peritoneal cavity through a catheterimplanted in the cavity. The dialysate contacts the patient's peritonealmembrane in the peritoneal cavity. Waste, toxins and excess water passfrom the patient's bloodstream through the peritoneal membrane and intothe dialysate. The transfer of waste, toxins, and water from thebloodstream into the dialysate occurs due to diffusion and osmosis,i.e., an osmotic gradient occurs across the membrane. The spentdialysate drains from the patient's peritoneal cavity and removes thewaste, toxins and excess water from the patient. This cycle is repeated.

[0006] There are various types of peritoneal dialysis therapies,including continuous ambulatory peritoneal dialysis (“CAPD”), automatedperitoneal dialysis and continuous flow peritoneal dialysis. CAPD is amanual dialysis treatment, in which the patient connects an implantedcatheter to a drain and allows a spent dialysate fluid to drain from theperitoneal cavity. The patient then connects the catheter to a bag offresh dialysate and manually infuses fresh dialysate through thecatheter and into the patient's peritoneal cavity. The patientdisconnects the catheter from the fresh dialysate bag and allows thedialysate to dwell within the cavity to transfer waste, toxins andexcess water from the patient's bloodstream to the dialysate solution.After a dwell period, the patient repeats the manual dialysis procedure.

[0007] In CAPD the patient performs several drain, fill, and dwellcycles during the day, for example, about four times per day. Eachtreatment cycle typically takes about an hour. Manual peritonealdialysis performed by the patient requires a significant amount of timeand effort from the patient. This inconvenient procedure leaves ampleroom for improvement and therapy enhancements to improve patient qualityof life.

[0008] Automated peritoneal dialysis (“APD”) is similar to CAPD in thatthe dialysis treatment includes a drain, fill, and dwell cycle. APDmachines, however, automatically perform three to four cycles ofperitoneal dialysis treatment, typically overnight while the patientsleeps. The APD machines fluidly connect to an implanted catheter. TheAPD machines also fluidly connect to a source or bag of fresh dialysateand to a fluid drain.

[0009] The APD machines pump fresh dialysate from the dialysate source,through the catheter, into the patient's peritoneal cavity and allow thedialysate to dwell within the cavity so that the transfer of waste,toxins and excess water from the patient's bloodstream to the dialysatesolution can take place. The APD machines then pump spent dialysate fromthe peritoneal cavity, though the catheter, to the drain. APD machinesare typically computer controlled so that the dialysis treatment occursautomatically when the patient is connected to the dialysis machine, forexample, when the patient sleeps. That is, the APD systems automaticallyand sequentially pump fluid into the peritoneal cavity, allow for adwell, pump fluid out of the peritoneal cavity and repeat the procedure.

[0010] As with the manual process, several drain, fill, and dwell cycleswill occur during APD. A “last fill” is typically used at the end ofAPD, which remains in the peritoneal cavity of the patient when thepatient disconnects from the dialysis machine for the day. APD frees thepatient from having to manually performing the drain, dwell, and fillsteps.

[0011] However, continuing needs exist to provide improved APD systems.For example, needs exist to provide simplified APD systems that areeasier for patients to use and operate. Further, needs exist to providelower cost APD systems and APD systems which are less costly to operate.Particularly, needs exist to clinically, economically and ergonomicallyimprove known APD systems.

[0012] APD systems need to be improved for home use. One common problemwith current home systems is that they are susceptible to electricalshock due to “leakage current”. Current that flows from or betweenconductors insulated from one another and from earth is called “leakagecurrent”. If any conductor is raised to a potential above earthpotential, then some current is bound to flow from that conductor toearth. This is true even of conductors that are well insulated fromearth, since there is no such thing as perfect insulation or infiniteresistance. The amount of current that flows depends on: (i) thepotential, (ii) the capacitate reactance between the conductor and earthand (iii) the resistance between the conductor and earth.

[0013] For medical equipment, several different leakage currents aredefined according to the paths that the leakage currents take. An “earthleakage current” is the current which normally flows in the earthconductor of a protectively earthed piece of equipment. In medicalequipment, impedance to earth from an enclosure is normally much lowerthrough a protective earth conductor than it is through the patient.However, if the protective earth conductor becomes open circuited, thepatient could be at risk of electrical shock.

[0014] “Patient leakage current” is the leakage current that flowsthrough a patient connected to an applied part or parts. It can eitherflow from the applied parts via the patient to earth or from an externalsource of high potential via the patient and the applied parts to earth.Other types of leakage currents include “enclosure leakage current”, and“patient auxiliary current”.

[0015] Leakage currents are normally small, however, the amount ofcurrent required to produce adverse physiological effects in patients isalso small. Accordingly, leakage currents must be limited as much aspossible by the design of the equipment and be within safety limits.

SUMMARY OF THE INVENTION

[0016] Generally, the present invention provides improved dialysissystems and improved methods of performing dialysis. More particularly,the present invention provides systems and methods for performingautomated peritoneal dialysis (“APD”). The systems and methods of thepresent invention automatically provide dialysis therapy by providingdialysis fluid to the patient and draining spent dialysis fluid from thepatient.

[0017] Also, the systems and methods of the present invention canperform various dialysis therapies. One example of a dialysis therapywhich can be performed according to the present invention includes anautomatic dialysis fluid exchange of a patient fill, dwell and a patientdrain. The dialysis system of the present invention can automaticallyperform dialysis therapy on a patient, for example, during nighttimewhile the patient sleeps.

[0018] To this end, in an embodiment a dialysis system is provided. Thesystem includes a fluid supply line. A disposable unit is in fluidcommunication with the fluid supply line. The disposable unit has atleast two flexible membranes that bond together at selected locationsand to a rigid plastic piece or manifold. The membranes can be single ordouble layer. One preferred membrane material is described herein. Themembranes seal to one another so as to define a fluid pump receptacleand a fluid heating pathway. The membranes and plastic manifold define anumber of flexible valve chambers. The disposable unit also fluidlycommunicates with a patient line and a drain line.

[0019] The manifold and other areas of the disposable unit includereduced or tapered edges that provide an area to seal the membranes. Thereduced thickness or tapered area requires less heat than the fullthickness, which reduces the heat sinking disparity between thethickness of the manifold of the disposable unit and the thinnerflexible membranes. The frame of the manifold is bowed or curved toprovide rigidity. The frame is also asymmetrical and designed to beplaced into the hardware unit in only one direction.

[0020] The hardware unit can be manually transported to a patient's homeand opened so that the patient can place a disposable unit therein andclosed so that the dialysis unit and the disposable unit cooperativelyform a pump chamber that enables dialysis fluid to be pumped to and fromthe patient. The hardware unit has an enclosure that defines a pumpshell, a valve actuator and a heater. The disposable unit is placed inand removed from the enclosure. The fluid pump receptacle of thedisposable unit and the shell of the hardware unit form a pump chamber.The pump chamber operates with a pump actuator, which is also locatedinside the transportable hardware unit.

[0021] When packaged, a plurality of tubes extend from the disposableunit. The ends of the tubes have connectors that attach to a singlebody. The body defines or provides a plurality of tip protectors thathold the tubes in an order according to steps of the therapy. The bodyis configured to slide into the hardware unit of the system from onedirection, so that a patient can readily pull the tubes and connectorsfrom the tip protector organizer.

[0022] The tip protector used to house the patient fluid connectorincludes a hydrophobic filter that allows air but not fluid to escape.This vented tip protector enables the system to be primed without havingto perform elevation balancing or controlled fluid metering. The systemperforms a prime by flowing fluid through the system and into thepatient fluid line until the dialysate backs up against the filter,causing a fluid pressure increase, which is sensed by the system. Thesystem then stops the pump.

[0023] The hardware unit also provides a controller. The controllerincludes a plurality of processors, a memory device for each processorand input/output capability. One of the processors coordinates operationof the pump actuator, the valve actuator and the heater with the variousstages of dialysate flow, such as the fill, dwell and drain stages. Theprocessor also controls or obtains feedback from a plurality ofdifferent types of sensors. The sensors include, among others, acapacitance fluid volume sensor, a dialysis fluid temperature sensor, apressure sensor, a vacuum sensor, an air detection sensor and amechanical positioning sensor.

[0024] In an embodiment, the system uses both preset motion control andadaptive pressure control to control the pressure of fluid within thepump receptacle. The system uses a preset pump motor acceleration toovercome system compliance (i.e., membrane and tubing expansion), whichwould not otherwise be readily overcome by known proportional,differential or integral control. After the system overcomes compliance,the system converts to an adaptive control using adaptive techniques forcontrolling pressure by precisely controlling the velocity of a pumpmotor shaft. The adaptive parameters are modified over time to fine tunethe system. This method is especially important for the patient fill anddrain cycles, wherein the patient can feel pressure fluctuations. Themethod also readily compensates for pressure variations due to bagheight, bag fullness, etc.

[0025] The capacitance fluid volume sensor indicates a volume of fluidin the pump chamber, wherein the sensor generates a voltage signal thatis indicative of the volume of fluid in the receptacle. The controllerreceives the voltage signal and converts the signal into an amount offluid or an amount of air within the flexible fluid receptacle of thepump chamber.

[0026] The pump actuator can be mechanically or pneumatically operated.When mechanically driven, a pump motor drives a vacuum source, such as apiston-cylinder, which pulls a vacuum on the membranes of the fluidreceptacle of the disposable unit. Here, a mechanical positioningsensor, such as an encoder, senses the angle of a pump motor shaftrelative to a home position and sends a signal to the controller,wherein the controller can adjust the pump motor accordingly. Theencoder also provides safety feedback to the controller, whereby thecontroller, once therapy starts, prevents the camshaft from rotating, toa position where the valves free fill the patient. When the pumpactuator is pneumatically operated, the system in an embodiment uses avacuum pump to pull apart the membranes of the fluid receptacle. Here,the system uses a vacuum sensor to sense the state of the vacuum pumpand a mechanical sensing device, such as a linear encoder, to sense thestate of a pump piston.

[0027] Thus, in an embodiment, the system maintains a negative pressureon one of the membranes of the fluid receptacle of the disposable unitto pull same away from the other membrane and draw dialysis fluid intothe fluid receptacle. The negative pressure on the active membrane isthen released, which pushes the membrane towards the other membrane anddispels the dialysis fluid from the pump receptacle. In anotherembodiment, a mechanical pump piston can be pneumatically attached toone of the membranes, wherein the system mechanically pulls the membraneaway from the other membrane. In an embodiment, the membrane is coupledto the pump piston through negative pressure. The pump also includes adiaphragm that is pulled to a bottom side of the piston head, whereinthe membrane is pulled to a top side of same. In a further embodiment,the system mechanically pushes one of the membranes while applying thenegative pressure to same.

[0028] The system also performs other necessary tasks automatically. Forexample, the system automatically heats the dialysate to a desiredtemperature while pumping dialysate to the patient. The heater heats thefluid heating pathway defined by the flexible membranes of thedisposable unit. In an embodiment, the heater includes an electricalheating plate. Alternatively, or in addition to the heating plate, theheater includes an infrared heating source. In an embodiment, the fluidheating pathway and the heater define an in-line heater that heatsdialysate as it travels from the supply bag to the patient.

[0029] The system employs a method of heat control that uses aknowledge-based algorithm and a fuzzy logic based algorithm. The formeruses laws of physics, empirical data and sensed inputted signals. Thelatter inputs a difference between desired and actual temperatures anduses fuzzy logic membership functions and fuzzy logic rules. Eachalgorithm operates at a different update frequency. Each algorithmoutputs a duty cycle, wherein the system weights the fuzzy logic basedduty cycle relative to the knowledge based duty cycle and produces anoverall heater control duty cycle. This method enables accuratedialysate temperature control.

[0030] The system automatically purges air from the dialysate, forexample, through the pump chamber. The system also senses a total volumeof fluid pumped to the patient, records and logs same. Furthermore, thesystem knows the instantaneous flow rate and fluid pressure of fluidentering or leaving the patient's peritoneal cavity.

[0031] The disposable unit includes a valve manifold. The manifolddefines a plurality of valve chambers. The hardware unit includes avalve actuator that selectively and sequentially presses against one ormore of the valve chambers. In an embodiment, a mechanically operatedvalve actuator includes a single camshaft and a plurality of cams. Thecams press against one of the membranes of the disposable unit to engagethe other membrane and block or disallow fluid flow. As stated above,the system uses a sensing device, such as a rotary encoder, to sense theangle of the camshaft relative to a home position, so that thecontroller can rotate the camshaft to open or close one or more valvesas desired. The single camshaft toggles back and forth between: supplyand pump chamber fill positions; patient drain and system drainpositions; and between pump chamber fill and patient fill positions.These positions are actuated by a unique rotational position on anoverall cam profile (i.e., the superposition of each of the individualcams as seen from the end of the camshaft).

[0032] The disposable unit of the present invention is provided in avariety of different forms. In an embodiment, the portion of thedisposable unit forming the heating path is formed by same membranesthat seal to the rigid member or manifold that forms the valve chambers.The same membranes also form the pump receptacle. In another embodiment,the disposable unit includes a first set of membranes that form the pumpreceptacle and the valve manifold via the rigid member. Here, thedisposable unit includes a second set of membranes, distinct from thefirst membranes, which form the fluid heating path. In an embodiment,medical grade tubing connects the first set of membranes to the secondset. In particular, the tubing enables the fluid heating path to fluidlyconnect to the valve manifold.

[0033] The disposable unit in another embodiment includes a firstflexible membrane and a second flexible membrane that house the pumpreceptacle, the fluid heating path and the rigid valve manifold. Thedisposable unit also includes a rigid frame that attaches to at leastone of the first and second flexible membranes. The rigid frame enablesa patient or operator to place the frame and the disposable unit intothe enclosure of the hardware unit of the automated dialysis system. Therigid frame is sized to securely fit into a dedicated place in theenclosure. The rigid frame further holds the disposable unit stablewhile patient or operator connects tubes to same. For example, the valvemanifold provides ports or other types of connectors for connecting to asupply line, a drain line and a patient line. In an embodiment, therigid frame extends around or circumvents the membranes including thepump receptacle, fluid heating path and valve manifold. In anembodiment, the rigid frame is plastic. In an embodiment, the rigidframe is bowed along at least two sides to increase the rigidly of thedisposable unit and to keep the disposable unit from deforming duringthe heat sealing portion of its manufacture.

[0034] In an embodiment, the rigid member or manifold of the disposableunit includes interfaces that allow the membranes to be more easilysealed to the manifold. The manifold edges are tapered to reduce theheat needed to form a cohesive bond between the membranes and theplastic valve manifold. The knife-like tapered edges also reduce oreliminate the gap between the top and bottom membranes, which minimizesthe opportunity for leaks to occur in the disposable unit. The chamferededges also reduce the likelihood that the heat sealing process will burnthrough the membranes.

[0035] The hardware unit described above includes a display device thatprovides dialysis system information. The display device also enablesthe patient or operator to enter information and commands into thecontroller. For example, the display device can include an associatedtouch screen that enables the patient or operator to initiate automaticflow of the dialysate through the disposable unit. The system begins topneumatically and/or mechanically pump dialysate through the pumpchamber, past the in-line heater and into the patient's peritonealcavity. Thereafter, the system automatically runs the other cycles ofdialysis therapy, for example, while the patient sleeps and/or at night.The automated system not only transfers dialysate from a supplycontainer to the patient, the system allows the dialysate to dwellinside the patient for an amount of time and automatically operates totransfer the dialysate from the patient to a drain.

[0036] The system provides a graphical user interface (“GUI”). The GUIin an embodiment employs an embedded web browser and an embedded webserver. The web browser and server operate on a main microprocessor forthe system. The GUI also employs instrument access and control software,which operates on the main system processor and on one or more delegateprocessors. The instrument access and control software controls lowerlevel devices, such as the heater and the pump. The GUI also providesintermediate software that allows the web browser to communicate withthe instrument access and control software.

[0037] The GUI displays a number of therapy set-up screens and a numberof dialysis treatment screens. The set-up screens generally walk thepatient through the set-up portion of the therapy. The system waits foran operator input before proceeding to the next set-up screen. Theset-up screens provide information to the patient in the form ofreal-life images of the equipment and through animations of the actionsneeded to connect the system to the patient.

[0038] The therapy treatment screens display the various cycles of thetherapy to the patient in real-time or substantially in-real time. Thetherapy treatment screens display information such as cycle time in botha graphical and quantitative manner. The therapy treatment screens donot require input from a patient, who may be sleeping while thesescreens are displayed. When the therapy is complete, the system onceagain displays a number of disconnection screens which, like the set-upscreens, wait for an input from the patient before performing an action.

[0039] The treatment screens are colored and lighted for night timeviewing, and may be easily seen from a distance of about ten to fifteenfeet, however, the screens are lighted so as not to wake a sleepingpatient. In an embodiment, the background of the screens is black, whilethe graphics are ruby red. In contrast, the set-up screens are lightedand colored for daytime viewing.

[0040] With the above embodiments, one advantage of the presentinvention is to provide improved systems and methods for performingdialysis.

[0041] Another advantage of the present invention is to provide improvedsystems and methods for performing peritoneal dialysis.

[0042] A further advantage of the present invention is to provide anautomated peritoneal dialysis system and method of operating same.

[0043] Still another advantage of the present invention is to provide anautomated peritoneal dialysis system that provides dialysis therapyadvantages.

[0044] Still a further advantage of the present invention is to providean automated peritoneal dialysis system that has economic advantages.

[0045] Yet another advantage of the present invention is to provide anautomated peritoneal dialysis system that has quality of lifeadvantages.

[0046] A still further advantage of the present invention is to providea disposable unit having bowed sides, which increase rigidity anddecrease flexing of disposable unit.

[0047] Moreover, an advantage of the present invention is to provide adisposable unit having tapered interfaces that decrease the heat sinkingof the semi-rigid manifold and provide a more robust seal.

[0048] Various features and advantages of the present invention canbecome apparent upon reading this disclosure including the appendedclaims with reference to the accompanying drawings. The advantages maybe desired, but not necessarily required to practice the presentinvention.

BRIEF DESCRIPTION OF THE FIGURES

[0049]FIG. 1 schematically illustrates an embodiment of an automateddialysis system of the present invention having a mechanically actuatedfluid pump.

[0050]FIG. 2 schematically illustrates another embodiment of anautomated dialysis system of the present invention having a fluidlyactuated fluid pump.

[0051]FIGS. 3A and 3B illustrate perspective views of the hardware unitand disposable unit of the present invention.

[0052]FIG. 4A is a plan view of one embodiment of the hardware anddisposable units of the present invention.

[0053]FIG. 4B is a cross-sectional view taken along line 4B-4B in FIG.4A, which shows one possible configuration of the system componentswithin the hardware unit.

[0054]FIGS. 5 and 6 illustrate additional embodiments of the disposableunit of the present invention.

[0055]FIG. 7 is a perspective view of one embodiment of a valve manifoldthat includes a reduced thickness interface for sealing to membranes ofa disposable dialysis unit.

[0056]FIG. 8 is a perspective view of one embodiment of a multiple tipprotector organizer of the present invention.

[0057]FIG. 9 is an elevation sectional view of the multiple tipprotector organizer illustrated in FIG. 8.

[0058]FIG. 10 is an elevation sectional view of one embodiment of avented tip protector of the present invention showing the tip protectorhousing a patient fluid line connector.

[0059]FIG. 11 is an elevation sectional view of one embodiment of thepatient fluid line connector that couples to the vented tip protector ofthe present invention.

[0060]FIG. 12 is an elevation sectional view of one embodiment of thevented tip protector of the present invention.

[0061]FIG. 13 is a sectional view of one embodiment of a single layerfilm structure for the disposable unit membranes of the presentinvention.

[0062]FIG. 14 is a sectional view of one embodiment of a multiple layerfilm structure for the disposable unit membranes of the presentinvention.

[0063]FIG. 15 is a perspective view of one embodiment of a valveactuator in combination with the fluid manifold of the presentinvention.

[0064]FIGS. 16A and 16B illustrate features of the camshaft and camarrangement of the present invention.

[0065]FIGS. 17A and 17B illustrate an embodiment of a mechanicallyoperated fluid pump and capacitance type fluid volume sensor of thepresent invention.

[0066]FIG. 18 illustrates an alternate embodiment of a fluidly operatedfluid pump and capacitance sensor of the present invention.

[0067]FIG. 19 is a graphical illustration of one embodiment of thepresent invention for the control of the pressure inside a fluid pumpthrough precise velocity control of a pump piston.

[0068]FIG. 20 is a schematic illustration of one embodiment of analgorithm of the present invention for performing proportional, integraland derivative type adaptive pressure control.

[0069]FIG. 21 is a graphical illustration of one embodiment of thepresent invention for the control of the pressure inside a fluid pumpduring repeated patient fill and pull from supply bag strokes.

[0070]FIG. 22 is a graphical illustration of one embodiment of thepresent invention for the control of the pressure inside a fluid pumpduring repeated patient drain and pump to drain strokes.

[0071]FIG. 23 is a schematic illustration of one embodiment of analgorithm of the present invention for adapting pressure errorcorrection parameters over time to optimize pressure control efficiency.

[0072]FIG. 24 is a table illustrating one set of the correctionparameters illustrated in connection with FIG. 23.

[0073]FIG. 25 is a schematic representation of one embodiment of aheater control method of the present invention.

[0074]FIG. 26 is a flow diagram of a knowledge based algorithm of themethod discussed in connection with FIG. 25.

[0075]FIG. 27 is a flow diagram of a fuzzy logic based algorithm of themethod discussed in connection with FIG. 25.

[0076]FIG. 28 is an electrical insulation diagram illustrating oneembodiment for providing double electrical insulation in the medicalfluid unit of the present invention.

[0077]FIG. 29 is a schematic representation of one embodiment of the webbased graphical user interface of the present invention.

[0078]FIGS. 30A to 30M are screen shots from a display device employingthe graphical user interface of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0079] The present invention relates to dialysis systems and methods ofperforming dialysis. In particular, the present invention relates to asystem and method for automatically providing peritoneal dialysistherapy to patients. The present invention provides automatic multipleexchanges of dialysis fluid to and from the patient's peritoneal cavity.The automatic exchanges of dialysate include drain, fill, and dwellperiods, which usually occur while the patient sleeps. A typical therapycan include three to five exchanges of dialysis fluid. The presentinvention, in an embodiment, provides a single pass system, wherein thedialysate passes through the peritoneal cavity only once before beingdisposed. While the present invention performs peritoneal dialysis, itis also suitable for other types of dialysis and other medical fluidtransfer operations.

I. The System Generally

[0080] Referring now to the drawings and in particular to FIG. 1, atypical therapy performed by the system 10 of the present inventionbegins by draining dialysis solution that is already in the patient'speritoneal cavity 12. The system 10 pumps fresh dialysate from one of aplurality of supply bags 14, through an in-line heater 16 to the patientor peritoneal cavity 12. After a dwell period in the peritoneal cavity12, the spent dialysate in the cavity is pumped out of the patient orcavity 12 to a drain 18 or other disposal means. The system 10 thenpumps fresh dialysate from the supply bags 14 to the patient orperitoneal cavity 12 and the procedure is repeated as defined in thetherapy protocol. The system 10 in an embodiment pumps a last bag ofdialysate (usually, a dialysate having a different formulation than thedialysate in the other supply bags) to the peritoneal cavity 12 for anextended dwell, such as a daytime dwell.

[0081] In an embodiment, the system 10 includes a mechanically operateddiaphragm pump 20. The mechanically operated diaphragm pump 20 employs apump motor 22 and a linear pump actuator 24. A vacuum may also be usedwith the mechanical actuator for the diaphragm pump 20, as described infurther detail below. In another embodiment illustrated in FIG. 2, thepump is completely fluidly activated.

[0082] In FIG. 1 the system 10 also includes a valve actuator 26, whichmechanically actuates valves V1 to V5. A controller 30 controls thevalve actuator 26 to open valves V1 to V5 as necessary to achieve thedesired direction of dialysate fluid flow. In an embodiment, the valveactuator 26 includes a valve motor 28 and a camshaft (illustratedbelow), which opens one or more of the valves V1 to V5 to achieve thedesired dialysate flow.

[0083] The controller 30 includes a plurality of processors and a memorydevice for each processor. The processors include a main microprocessorand a number of delegate processors. The main microprocessor runscertain higher level tasks such as the graphical user interface (“GUI”)described below. The delegate processors perform lower level tasks, suchas moving valves, reading sensors, controlling heater duty cycle, etc.An additional processor is provided solely for the purpose of trackingsafety parameters, such as heater plate and medical fluid temperature.For purposes of the present invention, except where otherwise specified,the term “processor 34” refers collectively to all of the processors andthe term “memory device 32” refers collectively to all of thecorresponding memory devices.

[0084] The controller 30 also includes an input/output (“I/O”) module36. The memory 32 stores a computer program that contains a step by stepsequence for the system 10 and configures certain outputs to occur uponspecified inputs. The processor 34 runs the program in memory 32. TheI/O module 36 accepts signal lines from various sensors. The I/O module36 also connects to power lines including input power lines (includingif battery powered) and power lines outputted to the various electricalcomponents.

[0085] The controller 30, in an embodiment, includes a video controller38, which may be a video card. The controller 30 also includes a displaydevice or video monitor 40 that displays medical treatment or dialysisinformation to a patient or operator. In an embodiment, the controller30 further includes a touch screen 42 that interfaces with the videomonitor 40 and electrically communicates with the I/O module 36. Thetouch screen 42 enables the patient or operator to input medicaltreatment or dialysis information into the controller 30.

[0086] The controller 30 controls the heater 16, the pump 20 and thevalve actuator 26 in a number of different phases that make up a singlemedical or dialysis treatment. In a first pump fill phase, controller 30activates the pump 20 to pump medical fluid or dialysate from one of thesupply bags 14. In FIG. 1, the controller 30 commands a vacuum source44, including an air pump motor 46, to pull a vacuum on both sides ofthe pump 20 through a first vacuum line 48 and a second vacuum line 50.The vacuum lines 48 and 50 pull respective vacuums through first andsecond pump chamber walls to suction one of a pair of opposing membranesinside the pump chamber against the interior of the pump chamber. Theother membrane is held against a piston head in the pump 20. The othermembrane alternatively temporarily or permanently mechanically attachesto the piston head, rendering the vacuum on the piston side of the pump20 unnecessary.

[0087] With the membranes maintained against the interior of the pumpchamber and the piston head, the controller 30 commands the linearactuator 24 to withdraw within the pump 20. The withdrawal causes themembranes inside the pump chamber to pull further apart. At this time,the controller 30 controls the valve actuator 26 so that only valve V1is open. The pulling apart of the membranes causes a negative pressureto occur in fill line 52, wherein the negative pressure pulls medicalfluid or dialysate from the supply bag 14, through the fill line 52,into a receptacle created by the opened membranes inside the pumpchamber of pump 20.

[0088] In a patient fill phase, with the negative pressure stillmaintained by the vacuum source 44, through the pump chamber walls, onthe interior membranes, the controller 30 causes the linear pumpactuator 24 to move upwards within the pump 20. The upward movement ofthe actuator 24 and an attached piston head provides a positivemechanical pressure that closes the membrane receptacle and therebypumps the medical fluid out of the pump 20. At this time, the controller30 controls the valve actuator 26 so that only valves V2 and V3 areopen. Consequently, all of the fluid exiting pump 20 is pumped through aheater line 54, past the in-line heater 16, through a catheter line 56,and into the patient, for example, the patient's peritoneal cavity 12.The catheter line 56 in an embodiment connects to a single lumencatheter, which is implanted into the patient 12. Although, in otherembodiments, the system 10 can employ a multi-lumen catheter.

[0089] The heater 16 in an embodiment, includes one or more electricalheating plates, which heat the medical fluid to roughly bodytemperature. The controller 30 energizes and de-energizes the heater 16as necessary to obtain the proper fluid temperature. The controller 30can close valves V2 and V3, located on opposing sides of the heater 16in the heater line 54, if the medical fluid is too hot or too cold. Theimproperly heated dialysate does not enter the peritoneal cavity 12.

[0090] The controller 20 repeats the pump fill phase and the heater fillphase until the patient's the peritoneal cavity 12, becomes full offluid according to the therapy protocol. In an embodiment, the volumeinside the pump is about thirty to fifty milliliters, and an adultpatient typically uses about two liters of dialysis fluid. Accordingly,the pump fill phase and the heater fill phase can be repeated on theorder of fifty times. In an embodiment, the pump actuator 24 maintains afluid pressure at the pump 20 of about three pounds per square inch(“psi”).

[0091] The system 10 provides a fluid volume sensor 60, which measuresthe actual volume of medical fluid that has been forced through the pump20. By summing multiple individual pump volumes, the controlleraccurately knows how much medical fluid or dialysate has been deliveredto the patient 12. The system 10 in an embodiment repeats the pump fillphase and the heater fill phase until the pump 20 has delivered apredetermined volume of medical fluid. The predetermined volume can beinputted into the controller 30 by a patient or operator via the touchscreen 42.

[0092] In a dwell phase, the controller 30 lets the medical fluid ordialysate remain within the patient 12 for an amount of time, which canbe controlled by the controller 30, the patient 12 or an operator. In anembodiment, the controller 30 determines the dwell time, but the patient30 or operator can override the system 10 and command that the system 10remove the medical fluid from the patient 12.

[0093] In a second pump fill phase, the medical fluid is removed fromthe patient 12. The controller 30 and the actuator 26 open valve V4,while shutting the remaining valves. With the vacuum source stillmaintaining a negative pressure on the membranes inside the pump 20, thelinear actuator 24 withdraws the pump piston within the chamber of pump20 and reopens the receptacle between the membranes. The negativepressure created by the opening receptacle pulls the medical fluid fromthe patient 12, through the catheter line 56 and into the membranereceptacle formed inside the pump 20.

[0094] In a drain phase, with the negative pressure still maintained bythe vacuum source 44, through the pump chamber walls, on the interiormembranes, the controller 30 causes the linear pump actuator 24 to moveupwardly within the pump 20. The upward movement of the actuator 24causes a positive mechanical pressure to close the membrane receptacleand thereby pump the medical fluid out of the pump 20. At this time, thecontroller 30 controls the valve actuator 26 so that only valve V5 isopen. Consequently, all of the fluid exiting pump 20 is pumped through adrain line 58 and into the drain 18. Drain 18 can be a drain bag or adrain pipe inside a home, a hospital or elsewhere.

[0095] One embodiment of the fluid volume sensor 60 is described in moredetail below in connection with the description of the diaphragm pump20. Besides the fluid volume sensor 60, the system 10 includes variousother desired types of sensors.

[0096] The system 10 includes temperature sensors 62, such as thesensors T1 to T4, which measure the temperature at relevant placeswithin the system 10. In an embodiment, the sensors 62 are non-invasive,however, any other types of temperature sensors may be employed. Asillustrated in FIG. 1, sensors T1 and T2 provide redundant post heaterfeedback of the fluid temperature to the controller 30. Sensor T3provides a temperature of the medical fluid prior to heating. Sensor T4provides the ambient temperature.

[0097] The system 10 also provides temperature sensors 62 that monitorthe temperature of the heater 16. In an embodiment, the heater 16 is anin-line plate heater. The in-line plate heater 16 can have one or moreheater plates, for example, two heater plates having a disposable unitplaced between same. Separate temperature sensors PT1 and PT2 areprovided to monitor the temperature of each of the plates of the plateheater. The system 10 can thereby control each plate heaterindividually.

[0098] The system 10 includes one or more air sensors 64, such as thesensor AS1, placed directly at the throat of the inlet and outlet of thepump 20. Another air sensor AS2 monitors air in the medical fluid afterit leaves the heater 16 and just before the final shut off valve V3leading to the catheter line 56. The controller 30 monitors the aircontent sensed by the air sensors 64 and thereby controls the system 10to perform any necessary air purge. The system 10 can separate anddischarge the air from the fluid or simply convey the air to the drain18. The system 10 also includes an air vent solenoid 66, which isoperated by the controller 30. The air vent solenoid 66 enables thesystem 10 to relieve the vacuum applied to one or both of the membranesin the pump 20.

[0099] The system 10 can accumulate air for various reasons. Forexample, the valves V1 to V5 and fluid lines, such as lines 52, 54, 56and 58 may contain air prior to priming the system 10. The supply bags14 may also introduce air into the pump 20. The patient 12 can alsoproduce certain gasses, which become entrained in the dialysate andenter the pump 20. Further, if minor leaks exist in the fluid disposableor the connections to the supply bag 14, the catheter at the patient 12,or the drain bag, the pump 20 can draw air in through the leaks.

[0100] The system 10 provides various fluid pressure sensors 68. Fluidpressure sensors FP1 and FP2 provide a redundant pressure reading of thefluid in the fill line 52 leading to the pump 60. The fluid pressuresensors 68 provide a signal to the controller 30 that indicates therespective fluid pressure at that location. Based on the signals fromthe pressure sensors FP1 and FP2, the controller 30 operates the fluidpumps and valves to obtain and maintain a desired fluid pressure. Asstated above, the system 10 maintains the pump pressure, for example, atabout three psi.

[0101] The system 10 also provides various valve pressure sensors 70.Valve pressure sensors VP1 to VP5 detect the fluid pressure at thevalves V1 to V5. The system 10 further provides one or more vacuumpressure sensors 72, for example, at the vacuum source 44, to ensurethat a proper vacuum is maintained on the membrane receptacle within thepump 20.

[0102] In an embodiment, the fluid pressure, valve pressure and vacuumsensors 68, 70 and 72, respectively, are non-invasive sensors. That is,the sensors do not physically contact (and possibly contaminate) themedical fluid or dialysate. Of course, the system 10 can include otherflow and pressure devices, such as flow rate sensors, pressure gauges,flowmeters, or pressure regulators in any suitable quantity and at anydesired location.

[0103] The system 10 also includes various positioning sensors. In anembodiment, the positioning sensors include a linear encoder 74 thatmonitors the position of the linear pump actuator 24 and a rotaryencoder 76 that monitors the angular position of the valve actuator 26or camshaft. An encoder is one type of positioning feedback device thatcan be employed. Other types of positioning feedback systems includeproximity sensors and magnetic pick-ups that sense a pulse, e.g., a geartooth of a gear attached to the camshaft, and output the pulse to acounter or microprocessor.

[0104] The encoders 74 and 76 also typically provide a pulsed output,which is sent to the controller 30. The pulsed output tells thecontroller 30 how many steps or how far the linear pump actuator 24 orthe valve actuator 26 is from a home position or home index 78. Forexample, the home position 78 can be the pump fully open or pump fullyclosed position for the linear encoder 74 and the zero degree positionfor the rotary encoder 76.

[0105] In an embodiment, the encoders 74 and 76 are absolute typeencoders that know the location of the home position 78 even after apower loss. In another embodiment, the encoders 74 and 76 areincremental encoders and a battery back-up is provided to the controllerso that the system 10 can maintain the location of the home position 78even when no external power is applied. Further alternatively, system 10can be programmed to automatically move the pump actuator 24 and thevalve actuator 26 upon power up until a home position is sensed, whereinthe system 10 can begin to run the main sequence.

[0106] Referring now to FIG. 2, an alternative system 100 isillustrated. The system 100 includes many of the same components havingthe same functionality (and the same reference numbers) as previouslydescribed. These components therefore do not need to be described againexcept to the extent that their functioning with the new components ofsystem 100 differs. The primary difference between the system 100 andthe system 10 is that the pump 120 of the system 100 is completelyfluidly actuated and does not use the linear pump actuator 24 of thesystem 10.

[0107] In the pump fill phases, described above, the controller 30activates the pump 120 to pump medical fluid or dialysate from one ofthe supply bags 14. To do so, the controller 30 commands vacuum source44 (shown separately from motor 46 in FIG. 2), including a vacuum pumpmotor 46, to pull a vacuum on both sides of the pump 120, i.e., on bothpump membranes, through vacuum lines 148 and 149. The vacuum pump motor46 in this embodiment includes a rotary encoder 76 and a home positionor home index 78. The rotary encoder 76 provides positional feedback ofa member 150 within the vacuum source 44. The system 100 therefore knowsif the vacuum source 44 can provide any additional suction or if themember 150 has bottomed out within the vacuum source 44.

[0108] To draw in medical fluid, the vacuum line 148 pulls a vacuumthrough first and second pump chamber walls to the pair of opposingmembranes inside the pump chamber. The vacuum pulls the membranesagainst the interior of the pump chamber. At this time, the controller30 controls the valve actuator 26 so that only valve V1 is open. Thepulling apart of the membranes causes a negative pressure to occur infill line 52, wherein the negative pressure pulls medical fluid ordialysate from the supply bag 14, through the fill line 52, into areceptacle created by the volume between the membranes inside the pumpchamber of pump 120.

[0109] In an alternative embodiment, the pump 120 maintains a constantvacuum on one of the membranes, wherein the opposing membrane does thepumping work. To pump fluid out, the vacuum on one or membranes isreleased. The membranes, which have been stretched apart, spring back toa closed position. This operation is described in detail below.

[0110] The system 100 also includes a slightly different valve manifoldthan the system 10. The system 100 includes one less valve than thesystem 10, wherein the system 100 does not provide an extra valve (V3 insystem 10) directly after the fluid heater 16. Obviously, those of skillin the art can find many ways to configure the valves and fluid flowlines of the systems 10 and 100. Consequently, the configuration of thevalves and fluid flow lines of the systems 10 and 100 as illustratedmerely represent practical examples, and the present invention is notlimited to same.

II. Hardware Unit and Disposable Unit

[0111] Referring now to FIGS. 3A, 3B, 4A and 4B, both of the systems 10and 100 include a hardware unit 110 and a disposable unit 160. Thehardware unit 110 in an embodiment is portable and can be transported toand from a person's home. The hardware unit 110 includes a housing 112that includes a base 114 and a lid 116. In an embodiment, the lid 116 ishinged to the base 114. Alternatively, the lid 116 is completelyremovable from the base. The lid 116 in either case opens to provideaccess to the interior of the housing 112, so as to allow the patient oroperator to place and remove the disposable unit 160 into and from thehardware unit 110. The hardware unit 110 can be made of any protective,hard, resilient and/or flexible material, for example, plastic or metalsheet, and can have a decorative and/or finished surface.

[0112] Once the disposable unit 160 is placed inside the hardware unit110, the operator closes the lid 116 and uses one or more locking orlatching mechanism 118 (FIG. 3B) to safely house the disposable unit 160within the hardware unit 110. FIG. 4A illustrates members 119 of thehousing 112 to which the latching mechanism 118 of the lid 116 attaches.The hardware unit 110 displays the video monitor 40, which can have anassociated touch screen 42 to input commands as described above.Alternatively, or in addition to the touch screen 42, the hardware unit110 can provide one or more electromechanical switches or pushbuttons43, 124, 125 and 127, analog controls 122 and/or lighted displays. Thepushbuttons or switches 43, 124, 125 and 127 and knob 122 enable thepatient or operator to input commands and information into the systems10 and 100. The video monitor 40 provides medical treatment information126 to the patient or operator.

[0113]FIG. 3B illustrates one set of dimensions for the hardware unit110 of the present invention. The size and weight of the presentinvention are less than previous automated dialysis system. This featurebelies the portability and ease of use of the system 10, 100 of thepresent invention. The size and weight enable the hardware unit 110 tobe shipped economically by standard overnight courier services. In theevent that the system 10, 100 of the present invention breaks down, areplacement unit can be economically shipped to the patient in time forthe next therapy.

[0114] The hardware unit 110 in an embodiment is approximately 23 to 30cm high and deep and in one preferred embodiment, as illustrated, about25 cm high and deep. The hardware unit 110 in an embodiment isapproximately 32 to 40 cm wide and in one preferred embodiment, asillustrated, about 34 cm wide. The internal volume of the unit 110 istherefore about 17,000 cm³ to about 36,000 cm³, and in one preferredembodiment, approximately 21,250 cm³ (1310 in³). Section view 4B aptlyillustrates the many components maintained within this compact space andthe efficient use of same. All these components and the hardware unit110 have a total mass of about six to nine kilograms (“kg) and in onepreferred embodiment about seven kilograms.

[0115]FIGS. 3A to 4B also illustrate that the architecture,configuration and layout of the hardware unit 110 provides an automatedsystem that is also convenient to use. The components of the system 10,100 with which the patient must interact are placed on the top, frontand sides of the unit 110. The flow control components are placed belowthe heater 116, which is placed below the disposable unit loadingstation. The monitor 40 and controls 43, 122, 124, 125 and 127 areplaced in the front of the unit 110.

[0116] The hardware unit 110 contains the pump 20 or 120 and the linearpump actuator 24 if system 10 is employed. The hardware unit 110 alsocontains the valve actuator 26 including the valve motor 28, the in-lineheater 16, the various sensors, the vacuum source 44 including the airpump motor 46 and the controller 30 as well as the other hardwaredescribed above. FIG. 4B illustrates that one of the pump chamber wallsof the pump 20 or 120 is disposed in the lid 116 of the housing. In FIG.4B, the heater 16 is disposed in the base 114 of the housing 112.Alternatively or additionally, the heater may be placed in the lid 116.The base 114 also contains the opposing pump chamber wall.

[0117] Referring now to FIGS. 3A, 4A, 4B, 5 and 6, various embodimentsof the disposable unit 160 are illustrated. In each of the embodiments,the disposable unit 160 includes a pair of flexible membranes, includingan upper flexible membrane 162 and a lower flexible membrane 164. Thedisposable unit 160 of FIG. 6 includes two pairs of flexible membranes,namely, membrane pair 166 and membrane pair 168. Each of the membranepairs 166 and 168 also includes the upper flexible membrane 162 and thelower flexible membrane 164.

[0118] The flexible membranes 162 and 164 can be made of any suitablesterile and inert material, such as a sterile and inert plastic orrubber. For example, the membranes 162 and 164 can be buna-N, butyl,hypalon, kel-F, kynar, neoprene, nylon, polyethylene, polystyrene,polypropylene, polyvinyl chloride, silicone, vinyl, viton or anycombination of these. One preferred material for the flexible membraneis described below in connection with FIGS. 13 and 14.

[0119] The membranes 162 and 164 are sealed together in various placesto create fluid flow paths and receptacles between the membranes 162 and164. The seals are heat seals, adhesive seals or a combination of both.FIGS. 3A, 4A, 5 and 6 illustrate that a generally circular seal 170creates a substantially circular fluid pump receptacle 172 between themembranes 162 and 164. The pump receptacle 172 operates with the fluidpumps. Instead of the seal 170, one alternative embodiment is for thebase 114 and lid 116 to press the membranes together to form the seal.FIGS. 4A and 5 illustrate that in an embodiment, the disposable unit 160provides a secondary seal 174 to protect the systems 10 and 100 in casethe primary seal 170 leaks or degrades during use.

[0120]FIGS. 3A, 4A and 4B illustrate that the fluid pump receptacle 172fits between the clamshell shapes of the pumps 20 and 120 in the lid116. The clamshell shapes defined by the base 114 and lid 116 of thehardware unit 110 together with the fluid pump receptacle 172 form thepump chamber of the pumps 20 and 120 of the present invention. Theclamshell shapes in the base 114 and lid 116 include one or more portswith which to draw a vacuum on the membranes 162 and 164. In thismanner, the membranes 162 and 164 are pulled towards and conform to theclamshell shapes in the base 114 and lid 116 and thereby create anegative pressure inside the receptacle 172 that pulls medical fluidfrom a supply bag 14 located outside the hardware unit 110, into thereceptacle 172.

[0121]FIGS. 3A, 4A, 5 and 6 illustrate that a generally rectangular,spiral seal 178 creates a spiral heating path 180 between the membranes162 and 164. The fluid heating path 180 runs from a valve manifold 190,through the spiral section, and back to the valve manifold 190. FIG. 4Aillustrates that the fluid heating path 180 fits between the heatingplates of the heater 16, which reside in the base 114 and lid 116 of thehardware unit 110. Providing a heat source on either side of the fluidheating path 180 enables the medical fluid to be quickly and efficientlyheated. In alternative embodiments, however, the heater 16 can includeonly a single heater on one side of the fluid heating path 180 definedby the disposable unit 160 or multiple heaters on each side of thedisposable unit 160.

[0122] The upper and lower membranes 162, 164 are attached to thedisposable unit 160 utilizing heat sealing techniques as describedherein. The membranes 162 and 164 is expandable so that when thedisposable unit 160 is placed between a predefined gap between the upperand lower plates of the heater 16, the membranes 162 and 164 expand andcontact the heater plates. This causes conductive heating to take placebetween the plates of the heater 16 and the membranes 162, 164 andbetween the membranes and the medical fluid. The predefined gap isslightly larger than the thickness of the disposable unit 160.Specifically, when dialysate moves through the fluid heating path 180 ofthe disposable unit 160, the membranes 162, 164 of the spiral woundfluid heating pathway 180 expand between the spiral seal 178 and touchthe plates of the heater 16.

[0123] A. Separate Sets of Membranes

[0124] The disposable unit 160 of FIG. 6 is similar to the disposableunits 160 of FIGS. 3A through 5. The in-line fluid heating path 180,however, is placed in a separate membrane pair 166 from the fluid pumpreceptacle 172 and the valve manifold 190, which are placed in aseparate membrane pair 168. A pair of flexible tubes 182 and 184, whichcan be any suitable medical grade tubing, fluidly connect the valvemanifold 190 to the fluid heating path 180. The tubes 182 and 184 can beconnected to the membrane pairs 166, 168 by any desired means, such as,heat sealing, bonding, press-fitting or by any other permanent orremovable fluid connection. When placed in the hardware unit 110, theheater 16 heats each side of the heater membrane pair 166, as in theother embodiments.

[0125] Separating the fluid heating path 180 from the fluid pumpreceptacle 172 and the valve manifold 190 enables the membranes of therespective pairs to be made of different materials. It is desirable thatthe membranes 162 and 164 of the heating pair 166 conduct or radiateheat efficiently. On the other hand, it is desirable that the membranes162 and 164 of the fluid flow pair 166 withstand the forces of suctionand mechanical actuation. It may therefore be desirable to usedissimilar materials for the membrane pair 166 and the membrane pair168.

[0126] The membrane pair 166, defining the heater fluid flow path 180,additionally defines alignment holes 176 that align with pegs protrudingfrom the base 114 or the lid 116 of the hardware unit 110. Each of theembodiments of the disposable unit 160 disclosed herein may be adaptedto include alignment holes 176, which aid the patient or operator inproperly placing the disposable unit 160 within the housing 112 of thehardware unit 110.

[0127] B. Rigid Frame and Bowed Sides

[0128] As shown in FIGS. 3A, 4A and 5, each of the embodiments of thedisposable unit 160 disclosed herein may also be adapted to provide arigid or semi-rigid member or frame 186, which in an embodiment,surrounds or substantially circumscribes the membranes 162 and 164 ofthe disposable unit 160. In an embodiment, the rigid member or frame 186is made of a sterile, inert, rigid or semi-rigid plastic, for example,from one of or a combination of the plastics listed above for themembranes 162 and 164. The frame 186 aids the patient or operator inproperly placing the disposable unit 160 within the housing 112 of thehardware unit 110.

[0129] In an embodiment, the housing 112 defines a pin or guide intowhich the frame 186 of the disposable unit 160 snugly fits. FIG. 5illustrates that the frame 186 defines an aperture 161 that fits ontothe pin or guide of the housing 112. The frame 186 can provide aplurality of apertures, such as the aperture 161, which fit onto a likenumber of pins or guides provided by the housing 112. FIG. 5 alsoillustrates that the frame 186 includes an asymmetrical member orchamfer 163. The chamfer 163 forms and angle, such as forty-fivedegrees, with respect to the other sides of the frame 186. The housing112 defines or provides an area into which to place the disposable unit160. The area has the asymmetrical shape of the frame 186 or otherwiseprovides guides that only allow the unit 160 to be placed in the housing112 from a single direction. The chamfer 163 and the cooperating housing112 ensure that when the patient places the disposable unit 160 in thehousing 112, the bottom of the disposable unit 160 is placed in thehousing 112 and the fluid inlets/outlets 196 face in the properdirection.

[0130] As discussed above, the disposable unit 160 includes a valvemanifold 190. In an embodiment, the valve manifold 190 is made of arigid or semi-rigid plastic, such as, from one of or a combination ofthe plastics listed above for the membranes 162 and 164. The valvemanifold 190 is covered on either side by the upper and lower membranes162 and 164 to thereby create a sealed and inert logic flow path for thesystems 10 and 100.

[0131] In FIG. 5, the manifold 190 defines holes 192 and slots 194. Theholes 192 define the location of the valves, for example, valves V1 toV5 of the system 10. The slots 194 define the fluid flow paths from thevalves to the fluid pump receptacle 172, the fluid heating path 180 orto fluid inlets/outlets 196. The fluid inlets/outlets 196 individuallylead to the supply bag 14, the catheter line 56, the patient 12 and thedrain 18. The fluid inlets/outlets 196 may have various configurationsand orientations, as contrasted by FIG. 3A. The drain 196 may also beadapted to connect to an external flexible tub via a method known tothose of skill in the art.

[0132] In an embodiment, the rigid or semi-rigid frame 186 includesbowed sides 187 and 189, as illustrated in FIG. 5. The bowed sides 187and 189 are formed with the frame 186 before the membranes 162 and 164heat seal or adhesively seal to the frame 186 and manifold 190. Theframe 186 and bowed sides 187 and 189 can be extruded plastic or plasticinjection molded. The frame 186 can include as little as one bowed side,any number less than all, or have all sides be bowed.

[0133] In the illustrated embodiment, the sides 187 and 189 bow outwardalthough they can alternatively bow inward. In a preferred embodiment,the sides are bowed in a direction of the plane of the frame 186 of thedisposable unit 160. The bowed sides 187 and 189 increase the rigidityof the frame 186 and the disposable unit 160. The disposable unit isaccordingly more easily placed in the housing 112 of the hardware unit110. The bowed sides 187 and 189 reduce the amount of flexing ordistortion of the frame 186 due to heat sealing or mechanically pressingmembranes 162 and 164 onto the frame 186 and manifold 190.

[0134] C. Heat Seal Interface

[0135] Referring now to FIG. 7, an embodiment for heat sealing themembranes 162 and 164 to the manifold 190 is illustrated. In anembodiment, the manifold 190 is made of a rigid or semi-rigid plasticmaterial as described above. Heat sealing the membranes 162 and 164 tothe semi-rigid manifold 190, which in an embodiment is an injectionmolded component, requires different processing parameters than heatsealing the individual membranes 162 and 164 together, for, example, atseal 170 of the fluid pump receptacle 172. In particular, heat sealingthe membranes 162 and 164 to the manifold 190 can require more heat,more pressure and more heating time. The semi-rigid or rigid manifold190 is appreciably thicker than the individual membranes 162 and 164.Consequently, relative to the thin membranes, the thicker manifold 190acts as a heat sink. The bond between the thin membrane and thickermanifold 190 therefore requires more heat or energy than the heat sealbond between the thin membranes 162 and 164.

[0136] As illustrated in FIGS. 3A, 4A, 5 and 6, the disposable unit 160requires both membrane to manifold and membrane to membrane seals. It isdesirable to heat seal the entire disposable unit 160 in one step orprocess for obvious reasons. It should also be obvious that the heatsealing process should be performed so as avoid burning or melting oneof the thin membranes 162 or 164.

[0137]FIG. 7 illustrates one embodiment for solving the heat sinkingdisparity between varying members. FIG. 7 illustrates a portion of themanifold 190, which is shown in its entirety in FIG. 5. In FIG. 5, themanifold 190 illustrates a port that connects to the fluid pumpreceptacle 172. This port is illustrated as port 205 in FIG. 7. FIG. 5also illustrates two ports extending from the manifold 190 that fluidlyconnect to the fluid heating path 180. These ports are illustrated asports 201 and 203 in FIG. 7. Both FIG. 5 and FIG. 7 illustrate that theinjection molded manifold 190 defines a plurality of holes 192 and slots194. The holes 192 operate with the valve actuator and the slots 194form fluid pathways when enclosed by the membranes 162 and 164.

[0138] To reduce the amount of heat necessary to seal the membranes 162and 164 to the manifold 190, the manifold 190 includes a side 193 havinga lesser thickness than the remaining portion of the manifold 190. Thethinner side 193 has less mass and therefore absorbs less localized heatthan would a manifold of constant thickness. The side 193 also definesor includes a tapered portion 195. The tapered portion 195 provides flatsurfaces on which to seal the membranes 162 and 164 and also positionsthe membranes 162 and 164 together so that in an embodiment a membraneto membrane seal may also be made in addition to the membrane tomanifold 190 seal.

[0139] The tapered edges 195 form an interface for the membranes 162 and164 to seal to the manifold 190, which occurs along continuous stretchesof the sides 193 of the manifold 190 that require sealing or that wouldotherwise come into contact with the medical fluid. Therefore, asillustrated in FIG. 5, the side of the manifold 190 defining theinput/output ports 196 does not need to be tapered as illustrated inFIG. 7. Also, as illustrated in FIG. 7, the tapered edges 195 of thethin sides 193 discontinue where the ports 201, 203, and 205 extend fromthe manifold 190.

[0140] The ports 201, 203 and 205 also form tapered edges 207. Taperededges 207 form an interface for heat sealing the parts to the membranes162 and 164. As described above, the tapered edges 207 of the ports 201,203 and 205 also enable a membrane to membrane seal to take placedirectly next to the membrane to tapered edge 207 seal. The taperededges 195 and 207 in a preferred embodiment gradually taper towards theknife-like edge. In other embodiments, the tapered edges 195 and 207 maytake on different forms or shapes, such as a rounded edge, a blunteredge or may simply be further reduced in thickness from side 193 of themanifold 190. As illustrated, the ports 201, 203 and 205 in anembodiment form ovular openings. The tapered ovular openings provide asmoother transition angle than would a circular outer diameter. Theovular openings perform as well as round openings from a fluid flowstandpoint as long as open area of the inner oval is not less than theopen area of a suitable circular port.

[0141] The ports 201, 203 and 205 also form raised portions 209. Theraised portions 209 form a bead of polymeric material along the tops ofthe ports 201, 203 and 205 and the tapered edges 207. The beads can beadditionally or alternatively placed along the tapered edges 195 and orthe sides 193. The raised portions or beads 209 provide an extra thinarea of plastic that melts or deforms to provide a flux-like sealantthat enables the membranes 162 and 164 to seal to the manifold 190. Thebeads create a concentrated strip of higher temperature plastic than thesurrounding plastic of the manifold 190. The membranes 162 and 164 sealto the manifold 190 without having to heat a larger area of the manifold190. The raised portions or beads 209 help to seal curved portions andcomers created by the manifold 190.

[0142] D. One-Piece Tip Protector Organizer and Vented Tip Protector

[0143] Referring now to FIG. 8, one embodiment of a one-piece tipprotector organizer 270 is illustrated. In the HOMECHOICE® peritonealdialysis system provided by the assignee of the present invention, adisposable set is prepackaged and provided to the patient. The patientopens up the package, wherein each of the components is sterilized andmaintained within the disposable set. The disposable set includes adisposable unit and a number of tubes emanating from the disposableunit. Like the present invention, the HOMECHOICE® disposable unitincludes a drain line tube that connects to one or more fill bag tubes,and a tube that connects to a patient transfer set. Each of these tubesrequires a separate tip protector. That is, after sterilizing the insideof the disposable unit and the tubes, for example, using ethylene oxide,the ends of the tubes would have to be capped off so that thesterilization of the inside of the system would be maintained. TheHOMECHOICE® system provides a separate tip protector for each tube.

[0144] The one-piece tip protector organizer 270 of the presentinvention provides a single body 272 (which may actually be made of aplurality of pieces) that defines or provides a plurality of tipprotectors 274, 276, 278 and 280. The vented tip protector 270 not onlyhouses and protects the connectors at the ends of the tubes emanatingfrom the disposable unit 160, the one-piece tip protector 270 alsoorganizes and orders the tubes according to the steps of the dialysistherapy. In the illustrated embodiment, the tip protector 274 is a tipprotector for a drain line connector 284 connected to a drain line 285that leads to the appropriate port of the disposable unit 160. The tipprotectors 276 and 278 are supply bag protectors that protect theconnectors 286 and 288 that connect to the ends of the tubes 287 and 289that run to a “Y” connection 287/289, wherein the leg of the “Y”connection 287/289 runs to the appropriate port of the disposable unit160. The tip protector 280 is a patient fluid line protector. The tipprotector 280 houses and protects a connector 290 that connects topatient tube 292, which runs to the appropriate port of the disposableunit 160.

[0145] Each of the tubes 285, the “Y” connection 287 and 289 and thepatient fluid tube 292 in an embodiment are made of polyvinylchloride(“PVC”) having an inner diameter of 4 mm and an outer diameter of 5 mm.As illustrated, the one-piece tip protector organizer 270 is adaptableto receive and protect various types of fluid connectors. The fluidconnector 284 that runs via tube 285 to the drain line port of thedisposable unit 160 is in an embodiment largely the same as the portthat emanates from the supply bags 14. The ports that emanate from thesupply bags 14 also include a membrane which is pierced by the sharpstem of the supply bag connectors 286 and 288. The drain line connector284 does not include the membrane of the supply bag 14 as it is notneeded. The tip protector 290 that connects to the end of the patientfluid tube 292 is discussed in detail below.

[0146] In one preferred embodiment, the system 10, 100 of the presentinvention provides two, six liter supply bags 14. The two, six literbags provide an economic amount of peritoneal dialysis fluid, which isenough fluid to provide a number of fill, dwell and drain cycles duringthe evening while the patient sleeps. The one-piece organizer 270therefore provides two tip protectors 276 and 278, which house andprotect the supply connectors 286 and 288. In alternative embodiments,the one-piece organizer 270 can define or provide any number of supplybag tip protectors. Any number of supply bags can be additionally linkedvia “Y” or “T” type tubing links.

[0147] The one-piece organizer 270 can provide additional tip protectorssuch as a last bag protector, which protects a line that runs to a bagthat holds enough peritoneal fluid, e.g., two liters, for a final fillfor the patient during the daytime. In this case, an additional last bagtube, not illustrated, would connect to a connector, which would be abag piercing connector, the same as or similar to the fill bagconnectors 286 and 288.

[0148] The body 272 of the tip protector organize 270 is in anembodiment also made of PVC. The tip protectors 274, 276, 278 and 280are injection molded or blow molded. Alternatively, the tip protectorscan be separately applied to the body 272. As seen in FIG. 8, one ormore of the tip protectors can include flutes, threads or otherprotrusions that aid in grasping and holding the respective tubeconnector. Further, while the organizer 270 is generally referred toherein as a “one-piece” organizer, the organizer 270 may itself becomprised of any number of pieces. “One-piece” refers to the featurethat a single unit houses a multitude of tip protectors.

[0149] The one-piece organizer 270 also includes a rim 294 that extendsoutwardly from the main portion of the body 272, and which circumventsthe main portion of the body 272. Referring now to FIG. 9, a crosssection of the one-piece organizer 270 illustrates that the rim 294tapers downwardly from the drain line tip protector 274 towards thepatient fluid tip protector 280. That is, the rim 294 is higher orthicker at the drain line end than it is at the patient fluid line end.This enables the one-piece tip protector organizer 270 to be mounted tothe hardware unit 110 in only one orientation.

[0150]FIG. 3A illustrates that the one-piece tip protector organizer 270in an embodiment slides into the hardware unit 110 vertically. Thehardware unit 110 includes or provides a pair of members 296 that extendoutwardly from a side wall of the hardware unit 110. FIGS. 3B and 4Aillustrate another embodiment, wherein the rim 294 of the organizer 270slides vertically into a notch 297 defined or provided by the base 114of the housing 112 of the hardware unit 110. The rim 294 of theorganizer 270 slides between the members 296 and the side wall of thehardware unit 110. The members 296 extend further and further outwardlyrunning towards the top of the hardware unit 110. The taper of themembers 296 corresponds to the taper of the rim 294 of the organizer 270so that the organizer 270 can only slide into the hardware unit 110vertically from one direction.

[0151]FIG. 9 also illustrates that the tip protectors 274, 276, 278 and280 can have various cross-sectional shapes. Each of the tip protectorsincludes a solid bottom and sides that seal around the respectiveconnectors 284, 286, 288 and 290, so that the one-piece organizer 270maintains the sterility of the system even after the patient removes thedisposable set from a sealed sterilized container. The one-pieceorganizer 270 illustrated in FIGS. 8 and 9 mounts in a sturdy fashion tothe side of the hardware unit 110. Via this solid connection, thepatient is able to remove the tubes 285, 287, 289 and 292 using only onehand in many cases. The interface between the hardware unit 110 and theorganizer 270 simplifies the procedure for the patient and provides asolid, sterile environment for the tubes and associated connectors untilused.

[0152]FIG. 3A also illustrates another possible embodiment wherein analternative one-piece organizer 298 is integral to or provided by theframe 186 of the disposable unit 160. Here, the tubes 196, indicatedgenerally, are horizontally organized as opposed to the verticalarrangement of the tip protector 270 in the housing 112. The horizontalone-piece organizer 298 illustrates that the concept of protecting andorganizing the tubes before use can be provided in a variety of placesand orientations in the system 10.

[0153] In one embodiment, the tip protector and organizer 270 structuresthe tubes 285, 287, 289 and 292 in a downwardly vertical order, suchthat the first tube that the patient is supposed to pull when startingthe dialysis therapy is provided on top, the next tubes that the patientis supposed to pull are provided in the middle and the final tube isprovided lowest on the vertically oriented one-piece organizer 270.According to one preferred protocol, the patient first removes the drainconnector 284 from the tip protector 274 and runs the drain line 285 toa toilet, drain bag or other drain. The patient then removes the supplyconnectors 286 and 288 and punctures the supply bags 14 (FIGS. 1 and 2).At this point, dialysate can be pumped to the disposable unit 160 andthroughout the system 10. The controller 30 of the system 10, 100 beginsa priming cycle, which is discussed in more detail below.

[0154] Once priming is complete, system 10, 100 prompts the patient toremove the primed patient line 292 and connect same to the transfer setimplanted into the patient. The transfer set (not illustrated) includesa catheter positioned into the patient's peritoneal cavity and a tuberunning to the catheter. The tube also includes a connector that couplesto the connector 290. At this point, system 10, 100 can begin to eitherdrain spent peritoneal fluid from the patient 12 to the drain 18 or pullnew fluid from one or both of the supply bags 14 and fill the patient'speritoneal cavity 12.

[0155] Referring now to FIGS. 10 to 12, one embodiment for the patientline tip protector 280 of the present invention is illustrated. TheHOMECHOICE® system produced by the assignee of the present inventionprimes the patient fluid line by allowing the patient connector to beheld vertically approximately at the same level as the supply bag. Inthis manner, when the HOMECHOICE® system primes the disposable unit,gravity feeds peritoneal fluid into the patient fluid line up to the endof the patient fluid connector. The patient fluid connector is open sothat air can freely escape when the peritoneal fluid is fed by gravitythrough the patient line. HOMECHOICE® system enables the patient fluidline to be primed without counting pump strokes or having to meter out aknown volume of dialysate, techniques which are complicated and prone tofailure.

[0156] The system 10, 100 of the present invention provides a differentapparatus and method of priming without having to calculate the amountof fluid that is needed to just reach but not surpass the patientconnector of the patient fluid line. FIG. 10 shows a cross-section ofthe patient fluid connector 290 that has been inserted into the ventedtip protector 280. FIG. 11 illustrates a cross section of the patientfluid connector 290 only. FIG. 12 illustrates a cross section of the tipprotector 280 only. A hydrophobic membrane 300 is placed on the outeredge of the tip protector 280. The tip protector 280 defines a fluidlumen 302 that runs through the entire length of the tip protector 280.The hydrophobic membrane 300 covers the fluid lumen 302. The hydrophobicmembrane 300 allows air to purge from inside the patient's fluid linebut does not allow water or peritoneal fluid to flow through same.

[0157] It should be appreciated that the vented tip protector 280including the hydrophobic membrane 300 is not limited to being placed inthe one-piece tip protector organizer 270. FIG. 9 illustrates that theone-piece organizer 270 does include the patient tip protector 280having the hydrophobic membrane 300 and the fluid lumen 302. The ventedtip protector 280 in an alternative embodiment, however, can be providedas a separate or stand alone tip protector, similar to the one used onthe HOMECHOICE® system provided by the assignee of the presentinvention.

[0158] Hydrophobic membranes, such as the hydrophobic membrane 300employed herein, are commercially available. One suitable hydrophobicmembrane is produced by Millipore, 80 Ashby Road, Bedford, Mass. 01730.FIG. 12 best illustrates that the hydrophobic membrane heat seals orsonically seals to the tip protector 280. The fluid lumen 302 in anembodiment is relatively small in diameter, such as approximately fiftyto seventy thousandths of an inch (1.25 to 1.75 mm).

[0159] The vented tip protector 280 and the patient fluid connector 290also cooperate so that when the system 10, 100 is completely primed, thetip protector 280 and connector 290 minimize the amount of fluid thatspills when the patient removes the patient fluid connector 290 from thetip protector 280. The connector 290 includes or provides a male lure304 that mates with a female lure 306 best seen in FIG. 10. The matinglures 304 and 306 prevent peritoneal fluid from filling the cavity ofthe tip protector 280, which must be wide enough to house the flange 308of the patient fluid connector 290. FIG. 12 illustrates that the sealinterface between the male lure 304 of the connector 290 and the femalelure 306 of the vented tip protector 280 reduces the volumesignificantly from an interior volume 310 existing around the male lure304 to the fifty to seventy thousandths diameter of the lumen 302.

[0160] To prime the system 10, 100 the patient removes the drain line285 from the tip protector 274 and places it into a tub, toilet or drainbag 18. The patient removes the two or more supply bag connectors 286and 288 and punctures seal membranes (not illustrated) of the supplybags 14. System 10, 100 may then automatically begin pump priming or maybegin pump priming upon a patient input. In either case, system 10, 100pumps fluid from one or both of the supply bags 14 through theconnectors 286 and 288 and tubes 287 and 289, into the disposaldisposable unit 160, out the patient fluid line 292 and into the patientfluid connector 290, which is still housed in the vented tip protector280 of the one-piece organizer 270. The organizer 270 is verticallyhoused in the hardware unit 110 as seen in FIGS. 3A and 3B.

[0161] When the peritoneal fluid reaches the patient fluid connector290, most all the air within the system 10 has been pushed through thehydrophobic membrane 300 attached at the end of the tip protector 280housed in the one-piece tip protector 270. The nature of the hydrophobicmembrane 300 is that it allows air to pass through but filters or doesnot allow water or peritoneal fluid to pass through same. Thus, when thefluid finally reaches the hydrophobic membrane 300, the lack of anyadditional space in which to flow fluid causes the pressure to increasewithin the system 10, 100. The system 10, 100 provides one or morepressure sensors, for example pressure sensors 68 (marked as FP1, FP2and FPT in FIGS. 1 and 2).

[0162] One or more of the pressure sensors 68 sense the increase inpressure due to the peritoneal fluid backing up against the hydrophobicfilter 300. The pressure sensor(s) sends a signal to the I/O module 36of the controller 30. The controller 30 receives the signal and isprogrammed in memory 32 to shut down the diaphragm pump 20, 120. In thismanner, the system 10 self-primes each of the fill lines 287 and 289,the disposal disposable unit 160 and the patient fluid line 292automatically and without need for controlled volume calculations orgravity feeding.

[0163] System 10, 100 also includes one or more safety features that maybe based upon a volume calculation. That is, under normal operations,the system 10, 100 does not control the priming using a volumecalculation. However, in the case where for example the patient removesthe patient fluid connector 290 from the vented tip protector 280 of theone-piece tip organizer 270 before the system 10, 100 senses a pressureincrease and stops the pumps 10, 100, the system 10, 100 can employ andalarm calculation, wherein the system 10, 100 knows that it has pumpedtoo much peritoneal fluid (e.g., a predetermined amount more than theinternal volume of the system) and shuts down pump 20, 120 accordingly.

III. Membrane Material for the Disposable Unit

[0164] Referring now to FIGS. 13 and 14, upper and lower membranes 162,164 can be fabricated from a monolayer film structure 312 (FIG. 13) or amultiple layer film structure 312 (FIG. 14). The upper and lowermembranes 162, 164 can be fabricated from a monolayer film structure 312(FIG. 13) or a multiple layer film structure 312 (FIG. 14). The film 312is constructed from a non-PVC containing polymeric material and mustsatisfy numerous physical property requirements. The film 312 must havea low modulus of elasticity so that it can be deformed under lowpressure to function as a pumping element. What is meant by low modulusis the film 312 has a modulus of elasticity when measured in accordancewith ASTM D882, of less than about 10,000 psi, more preferably less thanabout 8,000 psi and even more preferably less than about 5,000 psi andfinally, less than about 3,000 psi, or any range or combination ofranges defined by these numbers. The film 312 must have adequate thermalconductivity to allow for in-line heating. The film has a thermalconductivity of greater than 0.13 W/meters-°K when measured using a HotDisk® sold by Mathis Instruments Ltd. The film 312 must be capable ofbeing heat sealed to cassette 160. The film 312 must be capable of beingsterilized by exposure to gamma rays, by exposure to steam for a periodof time (typically 1 hour), and exposure to ethylene oxide withoutsignificant degradation of the film or having an adverse effect on thedialysis solution. Finally, the film 312 must be capable of beingextruded at high rates of speed of greater than 50 ft/min.

[0165] The monolayer structure 312 is formed from a blend of from about90% to about 99% by weight of a first component containing a styrene andhydrocarbon copolymer and from about 10% to about 1% of a melt strengthenhancing polymer and more preferably a high melt strengthpolypropylene.

[0166] The term “styrene” includes styrene and the various substitutedstyrenes including alkyl substituted styrene and halogen substitutedstyrene. The alkyl group can contain from 1 to about 6 carbon atoms.Specific examples of substituted styrenes include alpha-methylstyrene,beta-methylstyrene, vinyltoluene, 3-methylstyrene, 4-methylstyrene,4-isopropylstyrene, 2,4-dimethylstyrene, o-chlorostyrene,p-chlorostyrene, o-bromostyrene, 2-chloro-4-methylstyrene, etc. Styreneis the most preferred.

[0167] The hydrocarbon portion of the styrene and hydrocarbon copolymerincludes conjugated dienes. Conjugated dienes which may be utilized arethose containing from 4 to about 10 carbon atoms and more specifically,from 4 to 6 carbon atoms. Examples include 1,3-butadiene,2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene,chloroprene, 1,3-pentadiene, 1,3-hexadiene, etc. Mixtures of theseconjugated dienes also may be used such as mixtures of butadiene andisoprene. The preferred conjugated dienes are isoprene and1,3-butadiene.

[0168] The styrene and hydrocarbon copolymers can be block copolymersincluding di-block, tri-block, multiblock, and star block. Specificexamples of diblock copolymers include styrene-butadiene,styrene-isoprene, and selectively hydrogenated derivatives thereof.Examples of tri-block polymers include styrene-butadiene-styrene,styrene-isoprene-styrene,alpha-methylstyrene-butadiene-alpha-methylstyrene, andalpha-methylstyrene-isoprene-alpha-methylstyrene and selectivelyhydrogenated derivatives thereof.

[0169] The selective hydrogenation of the above block copolymers may becarried out by a variety of well known processes including hydrogenationin the presence of such catalysts as Raney nickel, noble metals such asplatinum, palladium, etc., and soluble transition metal catalysts.Suitable hydrogenation processes which can be used are those wherein thediene-containing polymer or copolymer is dissolved in an inerthydrocarbon diluent such as cyclohexane and hydrogenated by reactionwith hydrogen in the presence of a soluble hydrogenation catalyst. Suchprocedures are described in U.S. Pat. Nos. 3,113,986 and 4,226,952, thedisclosures of which are incorporated herein by reference and made apart hereof.

[0170] Particularly useful hydrogenated block copolymers are thehydrogenated block copolymers of styrene-isoprene-styrene, such as apolystyrene-(ethylene/propylene)-polystyrene block polymer. When apolystyrene-polybutadiene-polystyrene block copolymer is hydrogenated,the resulting product resembles a regular copolymer block of ethyleneand 1-butene (EB). This hydrogenated block copolymer is often referredto as SEBS. When the conjugated diene employed is isoprene, theresulting hydrogenated product resembles a regular copolymer block ofethylene and propylene (EP). This hydrogenated block copolymer is oftenreferred to as SEPS. When the conjugated diene is a mixture of isopreneand butadiene the selectively hydrogenated product is referred to asSEEPS. Suitable SEBS, SEPS and SEEPS copolymers are sold by Shell Oilunder the tradename KRATON, by Kurary under the tradename SEPTON® andHYBRAR®.

[0171] The block copolymers of the conjugated diene and the vinylaromatic compound can be grafted with an alpha,beta-unsaturatedmonocarboxylic or dicarboxylic acid reagent. The carboxylic acidreagents include carboxylic acids per se and their functionalderivatives such as anhydrides, imides, metal salts, esters, etc., whichare capable of being grafted onto the selectively hydrogenated blockcopolymer. The grafted polymer will usually contain from about 0.1 toabout 20%, and preferably from about 0.1 to about 10% by weight based onthe total weight of the block copolymer and the carboxylic acid reagentof the grafted carboxylic acid. Specific examples of useful monobasiccarboxylic acids include acrylic acid, methacrylic acid, cinnamic acid,crotonic acid, acrylic anhydride, sodium acrylate, calcium acrylate andmagnesium acrylate, etc. Examples of dicarboxylic acids and usefulderivatives thereof include maleic acid, maleic anhydride, fumaric acid,mesaconic acid, itaconic acid, citraconic acid, itaconic anhydride,citraconic anhydride, monomethyl maleate, monosodium maleate, etc.

[0172] The first component containing a styrene and hydrocarbon blockcopolymer can be modified by adding an oil, such as a mineral oil,paraffinic oil, polybutene oil or the like. The amount of oil added tothe styrene and hydrocarbon block copolymer is from about 5% to about40%. The first component can also contain a polypropylene up to about20% by weight of the first component. One particularly suitable firstcomponent is an oil modified SEBS sold by the Shell Chemical Companyunder the product designation KRATON G2705.

[0173] The melt strength enhancing polymer preferably is a high meltstrength polypropylene. Suitable high melt strength polypropylenes canbe a homopolymer or a copolymer of polypropylene and can have free endlong chain branching or not. In one preferred form of the invention, thehigh melt strength polypropylene will have a melt flow index within therange of 10 grams/10 min. to 800 grams/10 min., more preferably 10grams/10 min. to 200 grams/10 min, or any range or combination of rangestherein. High melt strength polypropylenes are known to have free-endlong chain branches of propylene units. Methods of preparingpolypropylenes which exhibit a high melt strength characteristic havebeen described in U.S. Pat. Nos. 4,916,198; 5,047,485; and 5,605,936which are incorporated herein by reference and made a part hereof. Onesuch method includes irradiating a linear propylene polymer in anenvironment in which the active oxygen concentration is about 15% byvolume with high energy ionization radiation at a dose of 1×10⁴ megaradsper minute for a period of time sufficient for a substantial amount ofchain scission of the linear propylene polymer to occur but insufficientto cause the material to become gelatinous. The irradiation results inchain scission. The subsequent recombination of chain fragments resultsin the formation of new chains, as well as joining chain fragments tochains to form branches. This further results in the desired free-endlong chain branched, high molecular weight, non-linear, propylenepolymer material. Radiation is maintained until a significant amount oflong chain branches form. The material is then treated to deactivatesubstantially all the free radicals present in the irradiated material.

[0174] High melt strength polypropylenes can also be obtained asdescribed in U.S. Pat. No. 5,416,169, which is incorporated in itsentirety herein by reference and made a part hereof, when a specifiedorganic peroxide (di-2-ethylhexyl peroxydicarbonate) is reacted with apolypropylene under specified conditions, followed by melt-kneading.Such polypropylenes are linear, crystalline polypropylenes having abranching coefficient of substantially 1, and, therefore, has no freeende long-chain branching and will have a intrinsic viscosity of fromabout 2.5 dl/g to 10 dl/g.

[0175] Suitable copolymers of propylene are obtained by polymerizing apropylene monomer with an α-olefin having from 2 to 20 carbons. In amore preferred form of the invention the propylene is copolymerized withethylene in an amount by weight from about 1% to about 20%, morepreferably from about 1% to about 10% and most preferably from 2% toabout 5% by weight of the copolymer. The propylene and ethylenecopolymers may be random or block copolymers. In a preferred form of theinvention, the propylene copolymer is obtained using a single-sitecatalyst.

[0176] The components of the blend can be blended and extruded usingstandard techniques well known in the art. The film 312 will have athickness of from about 3 mils to about 12 mils, more preferably from 5mils to about 9 mils.

[0177]FIG. 14 shows a multiple layer film having a first layer 314 and asecond layer 316. FIG. 14 shows the use of two layers but the presentinvention contemplates using more than two layers provided theabove-mentioned material property requirements are met. The first layer314 can be of the same polymer blend used to fabricate the monolayerstructure and in a more preferred form of the invention will define aseal layer for joining the film the cassette 160. The second layer 316can be made from non-PVC containing materials and preferably is selectedfrom polyolefins, polybutadienes, polyesters, polyester ethers,polyester elastomers, polyamides and the like and blends of the same. Atie layer or tie layers (not shown) may be required to adhere additionallayers to the first layer 314.

[0178] Suitable polyolefins include homopolymers and copolymers obtainedby polymerizing alpha-olefins containing from 2 to 20 carbon atoms, andmore preferably from 2 to 10 carbons. Therefore, suitable polyolefinsinclude polymers and copolymers of propylene, ethylene, butene-1,pentene-1, 4-methyl-1-pentene, hexene-1, heptene-1, octene-1, nonene-1and decene-1. Most preferably the polyolefin is a homopolymer orcopolymer of propylene or a homopolymer or copolymer of polyethylene.

[0179] Suitable homopolymers of polypropylene can have a stereochemistryof amorphous, isotactic, syndiotactic, atactic, hemiisotactic orstereoblock. In one preferred form of the invention the homopolymer ofpolypropylene is obtained using a single site catalyst.

[0180] It is also possible to use a blend of polypropylene and α-olefincopolymers wherein the propylene copolymers can vary by the number ofcarbons in the α-olefin. For example, the present invention contemplatesblends of propylene and α-olefin copolymers wherein one copolymer has a2 carbon α-olefin and another copolymer has a 4 carbon α-olefin. It isalso possible to use any combination of α-olefins from 2 to 20 carbonsand more preferably from 2 to 8 carbons. Accordingly, the presentinvention contemplates blends of propylene and αolefin copolymerswherein a first and second α-olefins have the following combination ofcarbon numbers: 2 and 6, 2 and 8, 4 and 6, 4 and 8. It is alsocontemplated using more than 2 polypropylene and α-olefin copolymers inthe blend. Suitable polymers can be obtained using a catalloy procedure.

[0181] It may also be desirable to use a high melt strengthpolypropylene as defined above.

[0182] Suitable homopolymers of ethylene include those having a densityof greater than 0.915 g/cc and includes low density polyethylene (LDPE),medium density polyethylene (MDPE) and high density polyethylene (HDPE).

[0183] Suitable copolymers of ethylene are obtained by polymerizingethylene monomers with an α-olefin having from 3 to 20 carbons, morepreferably 3-10 carbons and most preferably from 4 to 8 carbons. It isalso desirable for the copolymers of ethylene to have a density asmeasured by ASTM D-792 of less than about 0.915 g/cc and more preferablyless than about 0.910 g/cc and even more preferably less than about0.900 g/cc. Such polymers are oftentimes referred to as VLDPE (very lowdensity polyethylene) or ULDPE (ultra low density polyethylene).Preferably the ethylene α-olefin copolymers are produced using a singlesite catalyst and even more preferably a metallocene catalyst systems.Single site catalysts are believed to have a single, sterically andelectronically equivalent catalyst position as opposed to theZiegler-Natta type catalysts which are known to have a mixture ofcatalysts sites. Such single-site catalyzed ethylene α-olefins are soldby Dow under the trade name AFFINITY, DuPont Dow under the trademarkENGAGE® and by Exxon under the trade name EXACT. These copolymers shallsometimes be referred to herein as m-ULDPE.

[0184] Suitable copolymers of ethylene also include ethylene and loweralkyl acrylate copolymers, ethylene and lower alkyl substituted alkylacrylate copolymers and ethylene vinyl acetate copolymers having a vinylacetate content of from about 5% to about 40% by weight of thecopolymer. The term “lower alkyl acrylates” refers to comonomers havingthe formula set forth in Diagram 1:

[0185] The R group refers to alkyls having from 1 to 17 carbons. Thus,the term “lower alkyl acrylates” includes but is not limited to methylacrylate, ethyl acrylate, butyl acrylate and the like.

[0186] The term “alkyl substituted alkyl acrylates” refers to comonomershaving the formula set forth in Diagram 2:

[0187] R₁ and R₂ are alkyls having 1-17 carbons and can have the samenumber of carbons or have a different number of carbons. Thus, the term“alkyl substituted alkyl acrylates” includes but is not limited tomethyl methacrylate, ethyl methacrylate, methyl ethacrylate, ethylethacrylate, butyl methacrylate, butyl ethacrylate and the like.

[0188] Suitable polybutadienes include the 1,2- and 1,4-additionproducts of 1,3-butadiene (these shall collectively be referred to aspolybutadienes). In a more preferred form of the invention the polymeris a 1,2-addition product of 1,3 butadiene (these shall be referred toas 1,2 polybutadienes). In an even more preferred form of the inventionthe polymer of interest is a syndiotactic 1,2-polybutadiene and evenmore preferably a low crystallinity, syndiotactic 1,2 polybutadiene. Ina preferred form of the invention the low crystallinity, syndiotactic1,2 polybutadiene will have a crystallinity less than 50%, morepreferably less than about 45%, even more preferably less than about40%, even more preferably the crystallinity will be from about 13% toabout 40%, and most preferably from about 15% to about 30%. In apreferred form of the invention the low crystallinity, syndiotactic 1,2polybutadiene will have a melting point temperature measured inaccordance with ASTM D 3418 from about 70° C. to about 120° C. Suitableresins include those sold by JSR (Japan Synthetic Rubber) under thegrade designations: JSR RB 810, JSR RB 820, and JSR RB 830.

[0189] Suitable polyesters include polycondensation products of di-orpolycarboxylic acids and di or poly hydroxy alcohols or alkylene oxides.In a preferred form of the invention the polyester is a polyester ether.Suitable polyester ethers are obtained from reacting 1,4 cyclohexanedimethanol, 1,4 cyclohexane dicarboxylic acid and polytetramethyleneglycol ether and shall be referred to generally as PCCE. Suitable PCCE'sare sold by Eastman under the trade name ECDEL. Suitable polyestersfurther include polyester elastomers which are block copolymers of ahard crystalline segment of polybutylene terephthalate and a secondsegment of a soft (amorphous) polyether glycols. Such polyesterelastomers are sold by Du Pont Chemical Company under the trade nameHYTREL®.

[0190] Suitable polyamides include those that result from a ring-openingreaction of lactams having from 4-12 carbons. This group of polyamidestherefore includes nylon 6, nylon 10 and nylon 12. Acceptable polyamidesalso include aliphatic polyamides resulting from the condensationreaction of di-amines having a carbon number within a range of 2-13,aliphatic polyamides resulting from a condensation reaction of di-acidshaving a carbon number within a range of 2-13, polyamides resulting fromthe condensation reaction of dimer fatty acids, and amide containingcopolymers. Thus, suitable aliphatic polyamides include, for example,nylon 66, nylon 6,10 and dimer fatty acid polyamides.

[0191] In a preferred from of the invention, the cassette 160 isfabricated from a material that is adhesively compatible with the upperand lower membrane 162, 164. What is meant by adhesive compatibility isthe membrane can be attached to the cassette using standard heat sealingtechniques. One particularly suitable material is a polymer blend of apolyolefin and a styrene and hydrocarbon copolymer. More particularly,the polyolefin of the polymer blend is a polypropylene and even morepreferably a polypropylene copolymer with ethylene with an ethylenecontent of from about 1% to about 6% by weight of the copolymer. Thestyrene and hydrocarbon copolymer is more preferably an SEBS tri-blockcopolymer as defined above. The polypropylene copolymer shouldconstitute from about 70% to about 95% and more preferably from about80% to about 90% of the blend, and the SEBS will constitute from about5% to about 30% and more preferably from about 10% to about 20% SEBS. Ina preferred form of the invention, the polypropylene used to fabricatethe cassette will have a lower melting point temperature than the highmelt strength polypropylene used to fabricate the membrane. In apreferred form of the invention the polypropylene of the cassette 160will have a melting point temperature of from about 120° C.-140° C. andfor the film from about 145° C.-160° C. The cassette 160 can beinjection molded from these polymer blends.

[0192] The upper and lower membranes 162, 164 are attached to thecassette 160 utilizing heat sealing techniques. The film has a peelstrength of greater than 5.0 lbf/inch when tested with a tensileinstrument until film failure or bond failure. Also, when the film isattached to the cassette it can be deformed under a pressure of 5 psi.The film maintains its low modulus and deformability properties evenafter sterilization to continue to meet the pumping requirement. Thefilm has an extended shelf life. The film retains its pumping abilitieseven after two years shelf storage.

IV. Valve Actuator

[0193] Referring now to FIG. 15, one embodiment of an interface betweenthe valve actuator 26 and the valve manifold 190 is illustrated. Thevalve motor 28 (not illustrated) of the valve actuator 26 drives acamshaft 200 through a mechanical linkage determinable to those of skillin the art. In an embodiment, a single camshaft 200 attaches to a seriesof cams 202, for example, one of each of the valves in the system 10 or100. The cams 202 are fixed to the camshaft 200 and rotate in a one toone relationship with same.

[0194] The cams 202 drive pistons 204, which engage in a frictionreduced way with the cams, for example, via rollers 206. The cams 202drive pistons 204 up and down (only two of five cams shown havingassociated pistons to show other features of the actuator 26). When acam 202 drives its associated piston 204 upward, the piston 204 engagesone of the membranes 162 or 164 (typically the lower membrane 164, whichis not shown in FIG. 15 for clarity) and pushes the membrane up into therespective hole 192 defined by the rigid manifold 190. This action stopsthe flow of medical fluid or dialysate through the respective valve.

[0195] The pistons 204 are also spring-loaded inside a respectivehousing 208. When the camshaft 200 turns so that a lower cam profileappears below one of the pistons 204, the spring inside the housing 208pushes the piston 204 so that the roller 206 maintains contact with therespective cam 202. The piston 204 consequently moves away from therespective hole 192 defined by the rigid manifold 190, wherein themembrane 162 or 164, which has been stretched upward by the piston 204,springs back to its normal shape. This action starts the flow of medicalfluid or dialysate through the respective valve.

[0196] The motor 28 is of a type, for example a stepper or servo motor,that can rotate a fraction of a rotation and stop and dwell for anypredetermined period of time. Thus, the motor 28 can hold a valve openor closed for as long as necessary. The cams 202 are shaped to provide aunique combination of bumps and valleys for every flow situation. Incertain situations, such as with valves V2 and V3 of the system 10, thevalves always open and close together, so that both valves use the samecam 202 oriented in the same way on camshaft 200.

[0197] Referring now to FIGS. 16A and 16B, the camshaft 200 and cams 202are illustrated figuratively. FIG. 16A illustrates a composite camprofile 370, i.e., a combination of each of the cams 202 a to 202 fillustrated in FIG. 16B. FIG. 16B illustrates that the cams 202 a to 202f mount to the camshaft 200 via hubs 384. The hubs 384 may employ setscreens as is well known. camshaft 200 can also have indentations, etc.for aligning the hubs 384. In an alternative embodiment, one or more ofthe cams 202 a to 202 f may be integrally formed with the otherwisecamshaft 200. In an embodiment, the camshaft 200 is a single moldedpiece, which prevents the cams 202 a to 202 f from rotating with respectto one another. The single molded camshaft 200 supports or attaches to aplurality of or to all of the cams 202 a to 202 f.

[0198] As illustrated above in FIG. 15, each of the cams 202 a to 202 fof FIG. 16B drives a single piston 204 and roller 206 to operate asingle valve head 192 of the rigid manifold 190. The cams 202 a to 202 fopen or occlude the valve heads 192 according to the shape of therespective cam. FIG. 16B illustrates that the camshaft 200 supports sixcams 202 c to 202 f. FIG. 15 illustrates five cams 200. The cam providedin the embodiment of FIG. 16B may be to open a last bag, illustrated bythe “last bag valve open” position 382. Either of the systems 10 or 100may include a last bag. The last bag is a final dialysate fill of abouttwo liters into the patient before the patient disconnects from thesystem and resumes normal daily activities.

[0199] The valve motor 28 and the valve actuator 26 (FIGS. 1 and 2)rotate the camshaft 200 to open or close the valve heads 192 to create adesired solution flow path. The arrangement of the cams 202 a to 202 fon the camshaft 200 is made such that, at any time during the therapy,there is no more than one fluid path open at any given time. Further,when the valve actuator 26 rotates the camshaft 200 from one flow pathopen position to the next, the series of cams 202 a to 202 f close allthe valves for a moment of time. The closing of each of the valvesprevents dialysate from back-flowing or moving in the wrong direction.Still further, the cams 202 a to 202 f are arranged such that only onevalve head 192 of the valve manifold 190 of the disposable unit 160 maybe open at any given time. Therefore, there is no open fluid path in theevent of a system failure or inadvertent power down. This safety featureprevents dialysate from free-flowing into the patient 12 or overfillingthe patient 12.

[0200] The lid 116 for the housing 112 of the hardware unit 110 may befreely opened by an operator or patient to load the disposable unit 160into the hardware unit. When this occurs, the controller 30automatically commands the camshaft to rotate so that an “all valvesopen” position 372, illustrated by the composite profile 370, residesbeneath the rollers 206 and pistons 204. In the “all valves open”position 372, the camshaft 200 is rotated such that a depression existsunder each of the pistons 204 and associated rollers 206. Accordingly,the pistons 204 sit in a relatively low position, i.e., out of the way,when the operator or patient loads the disposable unit 160 and valvemanifold 190 into the hardware unit 110. This enables the patient oroperator to place a disposable unit 160 into the unit 110 withoutencountering an obstruction or opposing force by one or more of thepistons 206.

[0201] After the patient or operator loads the disposable unit into thehardware unit 110 and closes the lid 116, the controller 30automatically rotates the camshaft 200 so that an “all valves closed”position 386 a resides beneath the pistons 204 and rollers 206. Asillustrated, the “all valves closed” position 386 a resides adjacent tothe “all valves open” position 372. When the camshaft 200 is rotated tothe “all valves closed position” 386 a, no fluid can flow through thesystem 10, 100. As the camshaft 200 rotates from the “all valves open”position 372 to the first “all valves closed” position 386 a, amechanical interlock (not illustrated) is moved into the camshaft 200,which prevents the rotation of the camshaft 200 back to the “all valvesopen” position 372. This prevents uncontrolled flow of the dialysate,which could occur when each of the valve heads 192 is open, in the eventthat the operator tries to open the lid 116 during therapy.

[0202] In an alternative embodiment, an interlock can be providedthrough software. An encoder provides positional and velocity feedbackto the controller 30. The controller 30 therefore knows the position ofthe cam shaft 200. Thus, the controller 30 is able to prevent therotation of the camshaft 200 back to the “all valves open” position 372.

[0203] When the patient closes lid 116, a second mechanical interlock(not illustrated) locks the lid in place, so that the patient cannotopen the lid 116 during therapy. The system 10, 100 senses when thepatient has removed the patient fluid line 292 and connector 290 fromthe transfer set, implanted in the patient 12. Only then will the system10, 100 allow the patient to open the lid 116. The mechanical interlocksprevent free-filling, overfilling and the patient from tampering withthe system while it is running. The valve configuration provides a failsafe system that prevents fluid flow in the event a failure or powerdown.

[0204] In many instances, when the patient begins dialysis therapy, thepatient is already full of dialysate. In the illustrated embodiment ofFIG. 16A, therefore, the composite profile 370 provides the “all valveopen” position 372 next to the “from patient value open” position 374.The “from patient valve open” position resides next to the “drain valveopen” position 376. In this manner, upon therapy startup, camshaft 200is readily positioned to be able to cooperate with the pump 20, 120 todrain spent dialysate from the patient. It should be appreciated thatany of the cams 202 a to 202 f may be the cam that provides the “frompatient valve open” position 374, the “drain valve open” position 376,etc.

[0205] Between the “from patient valve open” position 374 and the “drainvalve open” position 376 resides a second “all valves closed” position386 b. Between each opening of a new valve and closing of a previouslyopened valve, each the valves is momentarily closed. The controller 30causes the motor (e.g., a stepper, servo or DC motor) and activator 26to toggle the camshaft 200 back and forth between the “from patent valveopen” position 347, past the “all valves closed” position 386 b, to the“drain valve open” position 376. In this manner, the pump 20, 120 isable to sequentially pull apart fluid from the patient 12 and dump it todrain 18.

[0206] When the system 10, 100 completes the initial patient draincycle, the controller 30 causes the motor 28 activator 26 to rotatecamshaft 200 past the “all valves closed” position 386 to the “supplyvalve open position” 378. To fill the patient full of fresh dialysate,the controller 30 causes the camshaft 200 to toggle back and forthbetween the “supply valve open” position 378 and the to patient valveopen position 380, each time passing over the “all valves closed”position 386 d. Again, for the drain and fill cycles, only one valvehead 192 is open at any given period of time. The toggling alwaysincludes an “all valves closed” position between the dosing of one valvehead 192 and the opening of another. The single pump sequentially pullsfluid into the disposable unit 160 and pushes fluid from same.

[0207] After the initial fill, camshaft 200 is positioned so that thecamshaft 200 can once again toggle back and forth between the “frompatient valve open” position 374, past the intermediate “all valvesclosed” position 386 b, to the “drain valve open” position 376. When thepatient is once again empty, the camshaft 200 is positioned so that thecamshaft may be toggled back and forth between the “supply valve open”position 378 and the “to patient valve open” position 380. The system10, 100 repeats this series of cycles as many times as necessary.Typically, the patient receives approximately 2 to 2.5 liters ofdialysate in a single fill cycle. The two supply bags 14 each hold sixliters of dialysate in an embodiment. This provides the system 10, 100with four to six complete fill, dwell and drain cycles, which areprovided, for example, through the night while the patient sleeps.

[0208] In many instances, the patient will receive a last bag fill atthe end of the therapy, which the patient will carry for the day. Toperform this procedure, the camshaft 200 toggles back and forth betweenthe “from patient valve open” position 374 to the “drain valve open”position 376 to dump the preceding fill of peritoneal fluid to drain 18.Thereafter, the camshaft 200 is positioned to toggle back and forthbetween the “last bag valve open” position 382 and the “to patient valveopen” position 380. In doing so, the camshaft 200 rotates past one ofall valves closed positions, namely, the “all valves closed position”386 e.

[0209] To prime the system, the camshaft 200 may be positioned andtoggled in a number of different ways. In one embodiment, the camshaft200 toggles back and forth between the “supply valve open” position 378and the “drain valve open” position 376, passing over the “all valvesclosed” position 386c. This toggling in cooperation with the pumping ofpump 20 or 120 causes the dialysate to flow from the supply bags 14,through the disposable unit 160, to drain 18. In another embodiment,using the vented tip protector 280 illustrated in connection with theFIGS. 8 to 12, the camshaft 200 toggles back and forth between the“supply valve open” position 378 and the “to patient valve open”position 380. This causes dialysate to flow from the bags 14, throughthe disposable unit 160, and into the patient fluid line 292 to the endof the vented tip protector 280. When dialysate reaches the hydrophobicmembrane 300 of the vented tip protection 28, the pressure in the system10, 100 rises, wherein a signal is received by the controller 30, whichcauses the pump 20, 120 to stop pumping and the camshaft 200 to stoptoggling.

V. Medical Fluid Pump

[0210] A. Pump Hardware and Operation

[0211] Referring now to FIGS. 17A and 17B, one embodiment of the pump 20is illustrated. The lid 116 of the hardware unit 110 defines an upperchamber wall 216. Disposed within the housing 112 of the hardware unit110 (FIGS. 3A to 4B) is a lower chamber wall 218. The chamber walls 216and 218 define an internal chamber 210. The chamber 210 can have anydesired shape, for instance the clamshell shape as illustrated in FIGS.17A and 17B.

[0212] The lower chamber wall 218 defines or provides a sealed aperture219 that allows a pump piston 212 to translate back and forth within thechamber 210. The piston 212 is attached to or integrally formed with apiston head 214. The piston head 214 in an embodiment has an outer shapethat is similar to or the same as an internal shape of the upper chamberwall 216.

[0213] The pump piston 212 connects to or is integrally formed with thelinear actuator 24. The linear actuator 24 in an embodiment is a device,such as a ball screw that converts the rotary motion of a motor 22 intothe translational motion of the piston 212. In one preferred embodiment,the motor 22 is a linear stepper motor that outputs a translationallymoving shaft. Here, the actuator 24 may simply couple the motor shaft tothe piston 212. The linear or rotary stepper motor provides quiet linearmotion and a very high positional resolution, accuracy andrepeatability. Stepper motors are commercially available, for example,from Hayden Switch and Instrument Inc., Waterbury, Conn.

[0214] As described above, the flexible fluid receptacle 172 (seen inFIG. 17A but not in FIG. 17B) is defined by the expandable upper andlower membranes 162 and 164, respectively, of the disposable unit 160.In FIG. 17A, when the pump 20 is full of medical fluid, the pump chamber210 and the membrane receptacle 172 have substantially the same shape.In FIG. 17B, when the pump 20 has displaced all or most all of themedical fluid, the pump chamber 210 maintains the same volume but themembranes 162 and 164 of the fluid receptacle 172 have collapsed tovirtually a zero volume along the interior surface of the upper chamberwall 216.

[0215] Vacuum source 44 for the pump 20 is described above in connectionwith FIG. 1. The vacuum source 44 exerts a vacuum on the upper membrane162, through the aperture or port 222. The aperture or port 222 extendsthrough the upper chamber wall 216. The vacuum source 44 exerts a vacuumon the lower membrane 164, through an aperture 221 defined or providedby housing 223, and through the port or aperture 220. The port oraperture 220 extends through the piston 212, including the piston head214. When a vacuum is applied, the lower membrane 164 seals against thepiston head 214. The upper membrane 162 seals against the upper chamberwall 216.

[0216] The port 222 fluidly connects to channels (not illustrated)defined by the interior wall of the upper chamber wall 216. The channelsextend radially outwardly from port 222 in various directions. Thechannels help to distribute the negative pressure applied through theport 222 to further enable the upper membrane 162 to substantiallyconform to the interior shape of the upper chamber wall 216. In asimilar manner, the outer surface of the piston head 214 can includeradially extending channels to further enable the lower membrane 164 tosubstantially conform, upon application of the vacuum, to the outersurface of the piston head 214.

[0217] The pump 20 also includes a diaphragm 232 tensioned between theupper and lower chamber walls 216 and 218, respectively. The diaphragm232 defines, together with the upper chamber wall 218, a known,predictable and repeatable maximum volume of dialysate, which can bedrawn from one or more of the supply bags 14 and transported to thepatient 12. The diaphragm 232 also enables the volume of a partialstroke to be characterized, which also enables accurate and repeatablevolume measurements.

[0218] The diaphragm 232 is disposed beneath the piston head 214 andaround the piston 212. When the vacuum is applied to the port oraperture 220, the diaphragm 232, as well as the lower membrane 164, arepulled against the piston head 214. When the piston head 214 is actuatedupwardly away from the lower chamber wall 218, with the vacuum appliedthrough aperture 220, the membrane 164 and the diaphragm 232 remaindrawn to the piston head 214. An inner portion of the membrane 164conforms to the shape of the outer surface of the piston head 214. Theremaining outer portion of the membrane 164 conforms to the shape of theexposed surface of the diaphragm 232.

[0219] The diaphragm 232 in an embodiment includes a flexible, moldedcup-shaped elastomer and a fabric reinforcement, such as fabricreinforced ethylene propylene diene methylene (“EPDM”). The fabric canbe integrally molded with the elastomer. The fabric prevents unwanteddeformation of the diaphragm while under pressure. The diaphragm 232 canstretch when the piston 212 and head 214 move downwardly towards thelower chamber wall 218, pulling the diaphragm 232 along the crimpededges of the upper and lower chamber walls 216 and 218. The diaphragm232 also moves and remains sealed to the piston head 214 when the piston212 and head 214 move upwardly towards the upper chamber wall 216.

[0220] In operating the pump 20, negative pressure is constantly appliedthrough the port 222 to hold the upper membrane 162 against the upperchamber wall 216. The manifold 190 of the disposable unit 160 (see FIGS.3A and 5) define a fluid port opening 230 to the membrane receptacle172. The fluid port opening 230 allows medical fluid or dialysate toenter and exit the membrane receptacle 172. The membrane receptacle 172seats in place with the crimped edges of the upper and lower chamberwalls 216 and 218. The seal 170 of the receptacle 172 may actuallyreside slightly inside the crimped edges of the upper and lower chamberwalls 216 and 218 (see FIG. 4A).

[0221] During a pump fill stroke, with the upper membrane 162vacuum-pressed against the upper chamber wall 216, and the lowermembrane 164 and the diaphragm 232 vacuum-pressed against the pistonhead 214, the motor 22/actuator 24 cause the piston head 214 to movedownwardly towards the lower chamber wall 218, increasing the volumewithin the flexible receptacle 172, and producing a negative pressurewithin same. The negative pressure pulls dialysate from the supply bags14 or the patient 12 as dictated by the current valve arrangement. Theopened receptacle 172 fills with fluid. This process occurs when thepump moves from the position of FIG. 17B to the position of FIG. 17A.FIG. 17A shows the pump 20 at the end of the stroke, with the receptacle172 fully opened (i.e., full of fluid).

[0222] During a patient fill or drain stroke, again with the uppermembrane 162 vacuum-pressed against the upper chamber wall 216, and thelower membrane 164 and the diaphragm 232 vacuum-pressed against thepiston head 214, the motor 22/actuator 24 cause the piston head 214 tomove upwardly towards the upper chamber wall 216, decreasing the volumewithin the flexible receptacle 172 and producing a positive pressurewithin same. The positive pressure pushes dialysate from the receptacle172 to the patient 12 or the drain 18 as dictated by the current valvearrangement. The receptacle 172 closes as the lower membrane 164 movesupward towards the upper membrane 162. This process occurs when the pumpmoves from the position of FIG. 17A to the position of FIG. 17B. FIG.17B shows the pump 20 at the end of the stroke, with the receptacle 172empty or virtually empty.

[0223] In the event that air (“air” for purposes of this inventionincludes air as well as other gases which may be present, particularlythose that have escaped from the patient's peritoneal cavity) enters thefluid receptacle 172, it must be purged to maintain accuracy. It shouldbe appreciated that if air enters between the membranes 162 and 164, thepresently preferred system 10, 100 does not have the ability to pull avacuum between the membranes 162 and 164. The elasticity of themembranes 162 and 164, however, naturally tend to purge air therefrom.In an alternative embodiment the system 10, 100 can be adapted toprovide a vacuum source that pulls a vacuum between the membranes 162and 164 to purge air therefrom.

[0224] To purge air from between the membranes, the system 10, 100 alsoprovides a positive pressure source. In systems 10, 100, for example,the pump motor 46 can be used in reverse of normal operation and,instead of producing vacuum source 44 (FIGS. 1 and 2), produce apositive pressure. The system 10 applies a positive pressure through theaperture or port 222 in the upper chamber wall 216 when air is detectedbetween the membranes 162 and 164 or elsewhere in the disposable unit160 or tubing. In one purge procedure, the controller 30 causes themotor 22/actuator 24 to move the piston head 214 to approximately ahalfway point in either the positive or negative strokes. With the uppermembrane 162 vacuum-pressed against the upper chamber wall 216, and thelower membrane 164 and the diaphragm 232 vacuum-pressed against thepiston head 214 maintained at the halfway point, the controller causesthe negative pressure source in through the aperture 222 to change to apositive pressure source, which pushes the upper membrane 162conformingly against the lower membrane 164, which is supported by thepiston head 214 and the diaphragm 232. Any air or fluid residing in thereceptacle 172 is purged to drain as is any air between the receptacle172 and drain 18.

[0225] B. Capacitance Volume Sensor

[0226]FIGS. 17A and 17B also illustrate that the pump 20 cooperates withan embodiment of the capacitance fluid volume sensor 60 of the system10. One embodiment of a capacitance sensor 60 is disclosed in greaterdetail in the patent application entitled, “Capacitance Fluid VolumeMeasurement,” Ser. No. 10/054,487, filed on Jan. 22, 2002, incorporatedherein by reference. The capacitance sensor 60 uses capacitancemeasurement techniques to determine the volume of a fluid inside of achamber. As the volume of the fluid changes, a sensed voltage that isproportional to the change in capacitance changes. Therefore, the sensor60 can determine whether the chamber is, for example, empty, an eighthfull, quarter full, half full, full, or any other percent full. Each ofthese measurements can be made accurately, for example, at least on theorder of the accuracy achieved by known gravimetric scales orpressure/volume measurements. The present invention, however, issimpler, non-invasive, inexpensive and does not require the medicaloperation to be a batch operation.

[0227] Generally, the capacitance C between two capacitor plates changesaccording to the function C=k×(S/d), wherein k is the dielectricconstant, S is the surface area of the individual plates and d is thedistance between the plates. The capacitance between the plates changesproportionally according to the function 1/(R×V), wherein R is a knownresistance and V is the voltage measured across the capacitor plates.

[0228] The dielectric constant k of medical fluid or dialysate is muchhigher than that of air, which typically fills the pump chamber 210 whenthe piston head 214 is bottomed out against the upper chamber wall 216,as illustrated in FIG. 17B. Therefore, the varying distance, Δd, of thelow dielectric displacement fluid between the expanding and contractingreceptacle 172 and the lower chamber wall 218 may have some effect onthe capacitance between ground capacitance plate 224 and the activecapacitance plate 226. Likewise the surface area, S, of the capacitanceplates and the moving membrane 164 may have some effect on thecapacitance. Certainly, the changing overall dielectric from the highdielectric dialysate replacing the low dielectric air (or vice versa)affects the overall capacitance between the plates 224 and 226.

[0229] As the membranes 162 and 164 expand and fill with medical fluid,the overall capacitance changes, i.e., increases. The sensor 60generates a high impedance potential across the grounded and activecapacitor plates 224 and 226. The high impedance potential is indicativeof an amount of fluid in the receptacle 172. If the potential does notchange over time when it is expected to change, the sensor 60 can alsoindicate an amount or portion of air within the receptacle 172.

[0230] A capacitance sensing circuit amplifies the high impedance signalto produce a low impedance potential. The low impedance potential isalso fed back to the guard plate 228, which protects the sensitivesignal from being effected by outside electrical influences. Theamplified potential is converted to a digital signal and fed to theprocessor 34, where it is filtered and or summed. The video monitor 40can then be used to visually provide a volume and/or a flowrateindication to a patient or operator. Additionally, the processor 34 canuse the summed outputs to control the pump 20 of the system 10, forexample, to terminate dialysate flow upon reaching predetermined overallvolume.

[0231] Referring now to FIG. 18, the pump 120 of the system 100 isillustrated in operation with the capacitance sensor 60 of the presentinvention. The pump 120 forms a clamshell with first and second portions246 and 248, which together form the pump chamber 250. The portions 246and 248 are rigid, fixed volume, disked shaped indentations in the base114 and lid 116 of the hardware unit 110. The clamshell first and secondportions 246 and 248 are closed and sealed on the pump receptacleportion 172 of the disposable unit 110, which includes the expandablemembranes 162 and 164.

[0232] An opening or aperture 252 is defined between the first andsecond clamshell portions 246 and 248 and the flexible membranes 162 and164. The opening 252 enables medical fluid, for example, dialysate, toenter and exit the chamber 250 between the membranes 162 and 164 in thereceptacle portion 172. The receptacle portion 172 fluidly communicateswith the valve manifold 190.

[0233]FIG. 18 shows the pump chamber 250 in an empty state with bothmembranes 162 and 164 in relaxed positions, so that the flexiblereceptacle portion 172 is closed. The empty volume state is achievedwhen the membranes 162 and 164 have collapsed so that substantially allthe fluid is removed from the sterile receptacle 172 and likewise thepump chamber 250.

[0234] The empty volume state can be achieved, for example, by allowingthe elastic membranes 162, 164 to return to their relaxed, unstressedstate as shown in FIG. 18. Also, both membranes 162 and 164 can beforced together against each other or against either one of the insideportions 246 and 248 of the pump chamber 250. When the pump chamber 250is in the full state, the medical fluid resides between the membranes162 and 164, wherein the membranes have been suctioned against the innerwalls of portions 246 and 248.

[0235] It should be appreciated that either one or both of the membranes162 and 164 can be moved towards and away from the clamshell portions246 and 248 by any suitable fluid activation device. In variousembodiments, the diaphragm pump is pneumatically or hydraulicallyactuated.

[0236] The diaphragm pump 120 of the system 120 does not require aseparate piston or mechanical actuator as does the pump 20 of the system10. The clamshell portions 246 and 248 define ports 254 and 256,respectively, to allow for movement of a displacement fluid (forexample, pneumatic or hydraulic fluid) into and out of the chamber areasoutside of the receptacle 172 to operate the diaphragm pump.

[0237] In an embodiment, the medical fluid, for example, dialysate, issuctioned into the receptacle 172 in the chamber 250. The receptacle172, defined by membranes 162 and 164, may be filled with medical fluidby applying negative pressures to one or both of the chamber ports 254and 256. The medical fluid can be emptied from the receptacle 172 byapplying a positive pressure to at least one of the ports 254 and 256,or by allowing the membranes 162 and 164 to spring back into shape. Inan alternative embodiment, the medical fluid, for example, dialysate, ispressurized from an external source to move in and out of the pumpchamber 250 between the membranes 162 and 164.

[0238] The clamshell portions 246 and 248 form and hold the capacitorplates of the capacitance sensor 60. In an embodiment, upper clamshellportion 246 includes an active metal or otherwise conductive capacitanceplate 258 between electrically insulative or plastic layers. A metalguard plate 260 is provided on the outer plastic layer of the upperclamshell portion 246. The guard plate 260 provides noise protection forthe high impedance signal that transmits from the active capacitor plate258.

[0239] As with the pump 20 of system 10, the active capacitor plate 258of upper clamshell portion 246 of the pump 120 of the system 100electrically couples to a capacitance sensing circuit. The guard plate260 likewise electrically couples to the feedback loop of thecapacitance sensing circuit as described above.

[0240] In an embodiment, lower clamshell portion 248 is also made of aninert plastic, wherein a metal capacitor plate 262 attaches to the outersurface of the lower clamshell portion 248. The metal capacitor plate262 disposed on the outside of the clamshell portion 248 electricallycouples to ground.

[0241] In one implementation, a negative pressure is constantlymaintained at the lower port 256, so that the lower membrane 164 ispulled to conform to the inner surface of the grounded clamshell portion248 during a multitude of fill and empty cycles. In this implementation,the upper membrane 162 does the pumping work. That is, when a negativepressure is applied to upper port 254 of upper clamshell 246, uppermembrane 162 is suctioned up against and conforms with the inner surfaceof upper clamshell 246. This action draws fluid from the supply bag 14,through the manifold 190, and into the receptacle 172. To expel fluid,the negative pressure is released from upper port 254, wherein uppermembrane 162 collapses to push the fluid from the receptacle 172.Alternatively, a positive pressure is applied through one or both ports.

[0242] In operation, the capacitance sensor 60 operates substantially asdescribed in FIGS. 17A and 17B. The receptacle 172 expands between theportions 246 and 248. A varying distance, Δd, of the low dielectricdisplacement fluid between the expanding and contracting receptacle 172and the portions 246 and 248 may have some effect on the capacitancebetween the ground plate 262 and the active plate 258. Likewise thesurface area, S, defined by the ground and active capacitance plates andthe expanding membranes may have some effect on the overall capacitance.Certainly, the changing overall dielectric from the high dielectricdialysate replacing the low dielectric air (or vice versa) affects theoverall capacitance between the plates 258 and 262.

[0243] As the membranes 162 and 164 expand and fill with medical fluid,the capacitance changes, i.e., increases. Each different amount ofmedical fluid within the chamber 250 has a unique overall capacitance. Aunique capacitance value can therefore be associated with each specificfluid volume in the chamber, for example, substantially empty, partiallyfall, or substantially full.

[0244] As an alternative to the capacitance volume sensor 60 describedabove, the volume of dialysate fluid flowing through the automatedsystems 10 and 100 can be determined using other methods, such asthrough an electronic balance. In such a case, the electronic balancekeeps track of the amount of dialysate that is supplied to the systemduring a priming of the system. The electronic balance also monitors anyadditional dialysate added to the system during dialysis treatment.

[0245] In other alternative embodiments, any of the systems describedherein can be sensed using other types of flowmeters or devicesemploying Boyle's Law, which are known to those of skill in the art.Further, various other types of fluid volume measurement or flowratedevices can be used with the automated systems 10 and 100, such asorifice plates, mass flow meters or other flow measuring devices knownto those of skill in the art.

VI. Precision Pressure Control

[0246] As discussed above, the system 10 employs a valve actuator 24 anda pump motor 22. In one embodiment the pump motor 22 is a stepper motor.In another embodiment, the motor 22 may be a DC motor or other type ofrepeatedly and accurately positionable motor. Each of these types ofmotors enable system 10 to position the piston 212 and piston head 214very accurately within the pump chamber 210. In the case of a highprecision rotary motor 22, the actuator 24 converts the rotary motioninto a translation motion precisely and moves the piston 212 back andforth within the chamber 210 within the accuracy and repeatabilityrequirement of the system. The resolution of the linear stepper motor inan embodiment is about 0.00012 inches per step to about 0.00192 inchesper step.

[0247] The pump motor 22 is also programmable. The programmable natureof the pump motor 22 enables acceleration, velocity and positional datato be entered into the controller 30, wherein the controller 30 uses theinformation to position the piston 212 and piston head 214 within thepump chamber 210, within an appropriate amount of time, to produce adesired amount of force or fluid pressure. The ability to preset theacceleration, velocity and position of the piston head 214 provides anadvantage over purely pneumatic systems that respond relativelysluggishly to pneumatic signals.

[0248] The flexible nature of the PVC medical tubing described, e.g., inconnection with FIG. 8 and the membrane material, described above inconnection with FIGS. 13 and 14, causes the system 10 to have what isknown as “compliance”. Compliance is caused when the system 10 attemptsto create fluid pressure, e.g., by moving the pump piston 212 and head214, but instead causes the flexible tubing and membranes to expand.With the flexible tubing and membranes, compliance is inevitable.Eventually, when the tubing and membranes have expanded to their elasticlimit, the pressure in the pump chamber 210 (i.e., in the receptacle172) and throughout the tubing rises sharply. It is desirable toovercome the compliance of the tubing and membranes 162 and 164 asquickly as possible so that pressure may be built to drive the fluid.

[0249] The present invention uses a hybrid pressure control system whichcombines the ability to preset the pump piston acceleration and velocitywith an adaptive pressure control scheme, which causes the pressure toachieve a desired pressure set point for any given stroke and causes thepressure to be fine tuned over time, i.e., over repeated strokes. Thatis, the present invention employs a method of controlling pressurewithin the system that seeks first to overcome system compliance andthen seeks to achieve a desired pressure set point. The output of thepresent method of controlling pressure within the pump chamber 210 isillustrated by the velocity and pressure curves of FIG. 19.

[0250] In general, the system 10 controls the pressure within thereceptacle 172 in the pump chamber 210 by controlling the velocity ofthe piston 212 and piston head 214. The velocity profile 390 of FIG. 19illustrates a single pump stroke that occurs over a time “t” beginningat the start of stroke position 392. In the beginning of the stroke, thevelocity ramps up at a preset acceleration 394. The preset acceleration394 is programmed into the controller 30. When the velocity due to thepreset acceleration 394 reaches a max velocity 396, the acceleration 394changes to a zero acceleration and the piston 212 moves at the constantmax velocity 396.

[0251] During the time period of the acceleration 394 and the maxvelocity 396, which is designated by the dashed vertical line 398, thecorresponding pressure as illustrated by a pressure curve 401 pressurecurve 400 ramps up beginning very slowly and exponentially increasing asthe time reaches that of the dashed line 398. In the initial curve,portion of the pressure, i.e., just after the start of stroke position,the pressure builds slowly as the compliance in the system is taken up.As the compliance is taken up, the pressure builds at faster and fasterrates.

[0252] When the pressure reaches a pressure proximity threshold 402, setin software, the software within the controller 30 converts from theprevious motion (acceleration, velocity, position) control to anadaptive control. It should therefore be appreciated that the method ofcontrolling pressure within the fluid pump of the present invention is ahybrid type of control method, employing a combination of techniques.

[0253] The motion control portion, accented by the acceleration 394 andmax velocity 396, represents a period in time when the method of controlis forcing the system to overcome the pressure compliance. Upon reachingthe pressure proximity threshold 402, the controller 30 causes thevelocity to sharply decelerate at deceleration 404. Deceleration 404reduces the velocity of the piston 212 and piston head 214 to a velocity406, which is a velocity that aids in the ability of the adaptivecontrol portion of the pressure control system to achieve a pressure setpoint 408. That is, without the programmed deceleration 404, theadaptive control portion would have a more difficult (i.e., longer) timecontrolling the velocity to make the pressure reach or substantiallyreach the pressure set point 408.

[0254] As explained in more detail below, the acceleration 394 isadaptively controlled in an embodiment, so as to reduce the amount ofinitial overshoot. The adaptive control over the acceleration 394 isfine tuned over time to further reduce the amount of initial overshoot.Each of these measures affects the amount of controlled deceleration 404needed.

[0255] After the controlled deceleration 404 reaches the velocity 406and until the time of the second dashed line 410, the system 10 operatesin an adaptive mode. The second vertical line 410 occurs near the end ofthe stroke. As illustrated, the adaptive portion of the stroke is brokendown into a number of areas, namely area 412 and area 414. Area 412 ischaracterized by the overshoot or undershoot caused by the programmedacceleration 394. In applying adaptive techniques, the adjustments orparameters that overcome area 414 error are tailored in software tocombat overshoot or undershoot. The area 414 focuses on attempting tominimize the error between the actual pressure curve 401 and thepressure set point 408. During the area 414, the parameters and adaptivemeasures are tailored in software reduce the oscillation of the pressurecurve 401 to achieve a pressure set point 408 as much as possible and asquickly as possible.

[0256] Upon reaching the time denoted by the dashed line 410, thepressure control method once again resumes motion control anddecelerates the velocity at a controlled and predetermined deceleration416 down to a final travel velocity 418, which is also the initialvelocity at the start of the stroke 392. In an alternative embodiment,the method can simply let the adaptive control continue past the timeline 410 and attempt to achieve the final travel velocity 418. After thetime line 410, the pressure along pressure curve 401 falls off towardszero pressure as illustrated by the area 418 of the pressure profile400. Comparing the pressure profile 400 to the velocity profile 390, itshould be appreciated that pressure remains in the receptacle 172 of thepump chamber 210 even after the stroke ends at time “t”. In some cases,the pressure overshoots as the piston 212 suddenly stops, wherein themomentum of the liquid produces a pressure spike after time “t”.

[0257] Referring now to FIG. 20, an algorithm 420 for employing theadaptive pressure control during the areas 412 and 414 of the pressureprofile 400 is illustrated. In an embodiment, the adaptive controlportion of the pressure control method employs a proportional, integraland derivative (“PID”) adaptive parameters. In the method, a pressurereading is taken from a pressure sensor which senses the pressure insidethe receptacle 172 of the pump chamber 210, and which provides apressure sensor input 422 to the controller 30, as illustrated by thealgorithm 420. Pressure sensor input 422 is sent through a digitalfilter 424, producing a measured variable 426. The measured variable 426is compared with a desired variable, i.e., the pressure set point 408illustrated in FIG. 19, wherein an error 428 is produced between themeasured variable 426 and the desired pressure set point 408.

[0258] Next, the error 428 is entered into a PID calculation 430, whichuses a proportional coefficient 432, and integral coefficient 434 and adifferential coefficient 436. The output of the PID calculation 430 isan adaptive pressure change 438. The controller 30 then changes thevelocity up or down to produce the pressure change 438.

[0259] In the pressure profile 400 of FIG. 19, the algorithm 420 of FIG.20 is constantly being performed during the adaptive areas 412 and 414.As discussed below, the corrective parameters, e.g., the coefficients432, 434 and 436, are used differently during the areas 412 and 414because correction in the area 412 is focused on minimizing overshootand undershoot, while correction in the area 414 however is focused onreducing error to zero about the pressure set point 408.

[0260] As described above, a single pump 20 is used in the system 10.The single pump 20 provides positive pressure during the patient fillstroke and the pump to drain stroke. The pump 20 also provides negativepressure during the pull from supply bag 14 stroke and the pull frompatient 12 stroke. Of the four strokes, it is most important toaccurately control the pressure during the patient fill and patientdrain stoke. It is not as critical to control the pressure when pumpingfluid from the supply bags 14 or when pumping fluid from the receptacle172 of the pump chamber 210 to drain 18. In the two positive pressurestrokes, one stroke, namely the patient fill stroke, it is critical toproperly control pressure. In the two negative pressure strokes, one ofthe strokes, namely the pull from patient stroke, it is critical toproperly control pressure. In the other two strokes, pressure iscontrolled without taxing the controller, motor 22 and disposable unit160 needlessly.

[0261] Referring now to FIG. 21, pressure and velocity curves are shownfor a number of strokes during the patient fill cycle. The upper profile440 shows the actual pressure 444 versus the desired pressure 442 inmilli-pounds per square inch (“mPSI”). The lower profile 450 showscorresponding velocity curves. In the pressure profile 440, the darkenedline 442 corresponds to the desired pressure in mPSI. The curve 444illustrates the actual pressure in mPSI. The curves 452 a, 452 b and 452c in the velocity profile 450 illustrate the piston velocities thatproduce the pressure fluctuations along the pressure curve 444 of thepressure profile 440. The velocity is measured in some increment ofsteps per second, such as milli-steps per second or micro steps persecond when the motor 22 employed is a stepper motor. Different steppermotors for use in the present invention may be programmed in differentincrements of a step. The actual velocity is therefore a function of theresolution of the stepper motor.

[0262] At time zero, the desired pressure 442 changes virtuallyinstantaneously to 2000 mPSI. The desired pressure curve 442 maintainsthis constant 2000 mPSI until reaching approximately 1.6 seconds, atwhich point the desired pressure 442 returns virtually instantaneouslyto zero. This step by the desired pressure curve 442 represents onecomplete patient fill stroke, wherein one full positive up-stroke of thepiston 212 and piston head 214 within the pump chamber 220 occurs. Inthis step it is critical to control pressure because dialysate is beingpumped into the patient's peritoneal cavity 12. The actual pressurecurve 444 ramps up exponentially and oscillates about the 2000 mPSI setpoint in the manner described in connection with FIG. 19. It should alsobe noted that the velocity curve 452 a follows a similar pattern to thatshown in FIG. 19.

[0263] At about 1.6 seconds, i.e., when the piston head has reached theupper chamber 216 of the valve chamber 210, controller 30 stops thepiston 212 from moving. The velocity of the piston head remains at zerountil approximately 3.4 seconds. In this period, the valves have allbeen closed via one of the “all valves closed” positions illustrated inconnection with FIG. 16A. As illustrated by pressure curve 444, residualfluid pressure resides within the pump chamber 210 even though thepiston head 214 is not moving.

[0264] At about time 3.6 seconds, the desired pressure curve 442switches virtuously instantaneously to −2000 mPSI. The pump 20 is nowbeing asked to expand and form a negative pressure that pulls fluid fromthe supply bags 14. During this stroke, it is not as critical to controlpressure as accurately in the patient fill stroke. Accordingly, themethod may be programmed to bypass the motion control portion of thepressure control method and simply adaptively seek to find the pressureset point along line 442. Dialysate moves through the fluid heating path180 of the disposable unit 160 (see FIGS. 3A and 5, etc.) during thepatient fill stroke. Much of the compliance, i.e., stretching of thesystem occurs when the fluid passes through the path 180. Pumping fluidfrom the supply bag 14, however, does not require the fluid to passthrough the heating path 180. The system 10 does not thereforeexperience the same level of compliance during this stroke. It ispossible to pump from the bags 14 without using the motion controlportion illustrated in connection with FIG. 19, since the lessenedcompliance may not require the “brute force” supplied by the controlledacceleration.

[0265] In FIG. 21, the pump couplets the stroke that pulls dialysatefrom the supply bag at about five seconds. The demand pressure alongcurve 442 returns to zero accordingly. Next, the valve switches to anall closed position, the controller 30 sets the piston speed to zero,and the piston head resides substantially along the lower chamber wall218, with the receptacle 172 full of fluid until approximately 6.8seconds has passed, wherein the system 10 repeats the patient fillstroke as described previously.

[0266] Referring now to FIG. 22, a pressure profile 452 and a velocityprofile 460 are illustrated for the patient drain stroke and the pump todrain stroke of the patient drain cycle. In the pressure profile 452,the demand pressure curve 454 illustrates that the controller calls fora negative 2500 mPSI to pull dialysate from the patient. The controller30 calls for a positive pressure of 2500 mPSI to push fluid from thereceptacle 172 of the pump chamber 210 to the drain bag 18. In thevelocity profile 460 shown below the pressure profile 452, the actualvelocity 462 in some increment of steps per second is illustrated. Itshould be appreciated that both velocity profiles 450 and 460 of FIGS.21 and 22 are absolute velocities and do not illustrate that the pumppiston 212 moves in positive and negative directions.

[0267] The actual pressure curve 456 of the profile 452 illustrates thatthe pressure is controlled to conform to the demand pressure line 454more closely during the pull from patient portion than during the pumpto drain portion of the profile 452. In an embodiment, the controller 30is programmed to provide a motion controlled velocity 464 for a portionof the pull from patient stroke and use an adaptive control during thetime “t_(adapt)”. The method also uses, in an embodiment, a controlleddeceleration 466 at the end of the pull from patient stroke.Alternatively, the method allows the PID control to seek to find zeropressure. Similarly, during the pump to drain stroke, the controller 30can switch to PID control only.

[0268] Referring now to FIG. 23, one embodiment of an algorithm 470illustrating the “fine tuning” adaptive control of the PID portion ofthe pressure control method of the present invention is illustrated.FIG. 23, like FIG. 20, includes a measured pressure variable 426 and adesirable pressure set point 408. The pressure error 472 represents anerror in either the overshoot area 412 or the oscillation area 414illustrated in the pressure velocity profile 400 of FIG. 19. For eacharea, the algorithm 470 looks at two error components, namely, the error474 determined in the current stroke and the error 476 stored forprevious strokes. The controller 30 compares the two errors 476 and 478and makes a decision as illustrated in decision block 478.

[0269] In the block 476, if the current stroke error 474 is less thanthe previous strokes error 476, the method uses the previous coefficientbecause the previous coefficient is currently having a desirable result.If the current stroke error 474 is greater than the previous strokeserror 476, two possibilities exist. First, the coefficient or correctivemeasure taken is not large enough to overcome the error increase. Here,the coefficient or corrective setting can be increased or another tacticmay be employed. Second, the previous corrective procedure may be havingan adverse impact, in which case the parameter connection can bereversed or another tactic can be employed. Obviously, to employalgorithm 470, the method provides that the controller 30 store themanner of the previous corrective attempts and outcomes of same. Basedon what has happened previously, the controller decides to increment ordecrease one or more of the parameters. The amount of increase ofdecrease is then applied to one or more coefficients stored in anincrement table 480. The adjusted or non adjusted increment is thensummed together with the currently used one or more coefficients 482 toform an adjusted one or more coefficients 484.

[0270] Referring now to FIG. 24, table 500 illustrates various differentcoefficients and adaptive perimeters for the pressure control method ofthe present invention. Certain of the coefficients and parameters applymore to the motion control portion of the profiles illustrated above,i.e., the set acceleration, deceleration and velocity portions of theprofiles. The motion control parameters, however, effect the error,which influences the adaptive parameters in the PID portion of thepressure control. Other parameters apply to the adaptive controlportions of the profiles. Adjusting the beginning stroke accelerationparameter 486 (illustrated by the acceleration 394 of the velocityprofile 390 of FIG. 19) affects the motion control portion of thepresent method. Acceleration as illustrated, affects overshoot and theefficient use of stroke time. That is, it is desirable to have a highacceleration to overcome compliance quickly, however, the cost may bethat overshoot increases. On the other hand, a lower acceleration mayreduce overshoot but require more time to overcome the compliance in thesystem.

[0271] The proximately threshold parameter 488 (illustrated by pressureline 402 in the pressure profile 400 of FIG. 19) also affects overshootand undershoot. Here, setting the pressure threshold 488 too low maycause undershoot, whereas setting the parameter 488 too high may causeovershoot. The DP/dt parameter 490 is the change in pressure for a givenperiod of time. This parameter seeks to achieve, for example in FIG. 19,a certain slope of the pressure curve 401.

[0272] The maximum travel velocity parameter 492, illustrated as line396 in the velocity profile 390 of FIG. 19, also affects overshoot andsubsequent resonance. Another corrective factor is the conversion topressure deceleration 494 corresponding to line 410 of FIG. 19. Themethod includes running the system without changing back to motioncontrol and instead leaving the system in the adaptive PID control. Theconversion to deceleration can have a large impact on the residualpressure remaining in the pump chamber 210 after the valves close.

[0273] The PID factors Kp, Kd and Ki, labeled 496, 498 and 502,respectively, affect the adaptive control portion of the present methodbut also affect, to a lesser extent, the controlled declaration at theend of the stroke. Each of the PID factors or parameters can be changedand adapted in mid-stroke. Also as illustrated in FIG. 23, the factorscan be changed so as to optimize the system over time.

[0274] Each of the above-described factors can be used to insulate thefluid pressure from changes in the environment outside of the system 10.For example, the factors can overcome changes due to physiological andchemical changes in the patient's abdomen. Also, the height of thepatient supply bags 14 affects the initial loading of the fluid pump 20.The parameters illustrated in FIG. 24 automatically overcome the changesdue to bag height. Further, as the patient sleeps through the night, thesupply bags 14 become less and less full, while the drain bag 18 becomesmore full, both of which affect the pump pressure. The parametersillustrated in FIG. 24 are automatically adjustable to compensate forthese changes and keep the system running smoothly.

[0275] Certain of the above-described factors is changed more and usedmore during the overshoot area 412 illustrated in the pressure profile400 of FIG. 19. Other factors and parameters are used and changed moreduring the oscillation portion 414 of the profile 400.

VII. In-Line Heater

[0276] In an embodiment, the inline heater 16 includes two electricalplate heaters, which are well known to those of skill in the art. Theplate heaters of the heater 16 have a smooth and flat surface, whichfaces the disposable unit 160. In an alternative embodiment, theautomated systems 10 and 100 provide an in-line heater 16 having a plateheater in combination with an infrared heater or other convectiveheater.

[0277] In the alternative dual mode type heater, both the plate heaterand, for example, the infrared heater are in-line heaters that heat themedical fluid that flows through the fluid heating path 180 of thedisposable unit 160. The radiant energy of the infrared heater isdirected to and absorbed by the fluid in the fluid heating path 180. Theradiant energy or infrared heater in an embodiment is a primary or highcapacity heater, which can heat a relatively large volume of cold fluidto a desired temperature in a short period of time.

[0278] The plate heater of the alternative dual mode heater in anembodiment is a secondary or maintenance heater which has a relativelylower heating capacity relative to the infrared heater. As describedabove, the plate heater uses electrical resistance to increase thetemperature of a plate that in turn heats the fluid flowing though thepath 180 adjacent to the plate.

[0279] The dual mode heater is particularly useful for quickly heatingcool dialysate (high heat energy demand) supplied from one of the supplybags 14 to the automated system 10 or 100. Initial system fills can becooler than later fills, and the system can lose heat during the dwellphase. The temperature of the dialysate at initial system fill cantherefore be quite low, such as 5° C. to 10° C. if the supply bags 14are stored in cold ambient temperature.

[0280] The plate heater and the infrared heater of the dual mode heaterembodiment of the heater 16 can be arranged in various configurationsrelative to each other. The dual mode heaters in an embodiment arearranged so that the fluid passes by the heaters sequentially (e.g.,first the plate heater and then the radiant or infrared heater). Inanother embodiment, the fluid passes by the heaters simultaneously (bothheaters at the same time). The fluid flow path past the heaters can be acommon flow path for both heaters, such as in the fluid heating path 180or include independent flow paths for each heater.

VIII. Fuzzy Logic for Heater Control

[0281] Similar to the controlling of the fluid pressure, the control ofthe plate heater 16 is also subject to a number of environmentalvariables. For example, the ambient temperature inside the patient'shome affects the amount of heat that is needed to raise the temperatureof the medical fluid to a desired temperature. Obviously, thetemperature of the dialysate in the supply bags 14 affects the amount ofheat that is needed to raise the fluid temperature to a desiredtemperature. Plate heater efficiency also affects the amount of heatingneeded. Further, the voltage provided by the patient's home is anotherfactor. Typically, a doctor or caregiver prescribes the temperature ofthe dialysate for the patient to be controlled to around a temperatureof 37° C. It is, therefore, desirable to have a method of controllingthe heater 16 to correct for outside temperature gradients so as tomaintain the proper patient fluid temperature.

[0282] Referring now to FIG. 25, one embodiment of a heating controlmethod 510 is illustrated. The method 510 includes two separatelyperformed algorithms 520 and 530 that operate in parallel to form anoverall output 544. The algorithm 520 is termed a “knowledge-based”control algorithm. The knowledge-based control algorithm is based onknowledge, such as empirical data, flow mechanics, laws of physics andlab data, etc.

[0283] The knowledge-based algorithm 520 requires a number of inputs aswell as a number of constant settings. For example, the controlalgorithm 520 requires an input pulsatile flowrate. As illustratedbelow, the pulsatile flowrate is actually calculated from a number ofinput variables. The system 10, 100 of the present invention providesfluid to the patient 12 in pulses, rather than on a continuous basis. Itshould be readily apparent from the discussion based on FIGS. 16A and16B, that when all valve heads in the disposable are closed, no fluidcan flow through the fluid heating pathway to the patient. The flowrateof fluid to the patient is therefore a pulsatile flowrate, wherein thepatient receives the dialysate in spurts or pulses. It is difficult tocontrol fluid temperature with this type of flowrate. To this end, themethod 510 provides the dual algorithms 520 and 530.

[0284] Besides the pulsatile flowrate, the knowledge-based controlalgorithm 520 also receives a measured, i.e., actual, fluid inlettemperature signal. Further, the algorithm 520 stores the plate heaterefficiency, which is based on empirical data. In one embodiment, theupper and lower plates of the plate heater 16 are around 95% efficient.Algorithm 520 also inputs the total heater power, which is derived fromthe voltage input into the system 10, 100. Residential voltage may varyin a given day or over a period of days or from place to place.

[0285] The algorithm 520 also inputs the desired outlet fluidtemperature, which is a constant setting but which may be modified bythe patient's doctor or caregiver. As illustrated in FIG. 25, thedesired outlet fluid temperature is inputted into both theknowledge-based control algorithm 520 and the fuzzy logic based controlalgorithm 530. As discussed in more detail below, the knowledge-basedcontrol algorithm 520 outputs a knowledge-based duty cycle into asummation point 544.

[0286] With respect to the fuzzy logic-based control algorithm 530, thedesired fluid temperature is inputted into a comparison point 514. Thecomparison point 514 outputs the difference between the desired fluidtemperature and the actual measured fluid temperature exiting theheating system 548. The fuzzy logic-based control algorithm 530therefore receives a change in temperature ΔT as an input. As describedbelow, the fuzzy logic-based control algorithm 530 employs the conceptsand strategies of fuzzy logic control to output a fuzzy logic dutycycle.

[0287] In the method 510, the knowledge-based duty cycle is adaptivelyweighted against the fuzzy logic-based duty cycle. In an alternativeembodiment, the system predetermines a relative weight. In the method510, the fuzzy logic-based duty cycle is weighted, i.e., provided aweight factor as illustrated in block 542. For example, if the fuzzylogic-based duty cycle is given a weight factor of one, then the fuzzylogic-based duty cycle is weighted equally with the knowledge-based dutycycle. If the fuzzy logic-based duty cycle is given a weight factor oftwo, the fuzzy logic-based duty cycle is given twice the weight as theknowledge-based duty cycle. The weight factor in block 542 can changeover time and/or be optimized over time.

[0288] It should be appreciated that the weighting block 542 couldalternatively be placed in the knowledge-based duty cycle output. Asdiscussed below, however, the update rate of the fuzzy logic controlloop is substantially higher than the update rate of the input signalsentered into the knowledge-based control algorithm 520. It is thereforeadvantageous to weight the fuzzy logic-based duty cycle, as opposed tothe knowledge-based duty cycle.

[0289] The weighted fuzzy logic-based duty cycle and the knowledge-basedduty cycle are summed together at summing point 544 to produce anoverall heater duty cycle. Duty cycle is one way to control the powerinput and, thus, the plate temperature of the heater. Controlling theduty cycle means controlling the percentage of a time period that fullpower is applied to the heater, for example, plate heater 16. In analternative embodiment, the output of the parallel control algorithms520 and 530 could be a percentage of full power applied at all times.Still further, the output of the parallel control algorithms 520 and 530could be a percentage of full power applied for a percentage of a timeperiod. For purposes of illustration, the method 510 is described usinga duty cycle output which, as explained, is the percent of a time periodthat full power is applied to the heater.

[0290] As described herein, the heating system 548 (i.e., heater 16) inone preferred embodiment is a plate heater, wherein upper and lowerplates are disposed about a fluid heating path of the disposable unit160. It should be appreciated, however, that the method 510 is equallyapplicable to the infrared heater previously described. Further, themethod 510 is equally applicable to the combination of different typesof heaters, such as, the combination of a plate heater and an infraredheater.

[0291] The method 510 uses multiple temperature sensors, such as thesensors 62 illustrated in FIGS. 1 and 2, which sense the temperaturefrom different areas of the method 510. One sensor senses the fluidoutlet temperature, which feeds back from the heating system 548 to thecomparison point 514. Another two temperature sensors sense thetemperature of the top plate and the bottom plate and feed back to thetemperature limit controller 546, located in software.

[0292] As illustrated, before the summed heater duty cycle is inputtedinto the heating system 548, the system determines whether the top andbottom heating plats are already at a maximum allowable temperature.There exists a temperature above which it is not safe to maintain theplates of the plate heater. In a situation where one or both of theplates is currently at the temperature limit, the method 510 outputs azero duty cycle, regardless of the calculations of the knowledge-basedcontrol system 520 and the fuzzy logic-based algorithm 530. To this end,the temperature of the top and bottom plates is fed back into the block546, wherein the software only allows a heater duty cycle to be appliedto the heating system 548 if the current temperature of the top andbottom plates is less than the limit temperature.

[0293] In an embodiment, if one of the plates is at the limittemperature, the method 510 provides a zero duty cycle to both plateheaters, even though one of the plate heaters may be below the limittemperature. Further, the software may be adapted so that if the actualtemperature of the plate heater is very close to the limit temperature,the method 510 only allows the duty cycle be at or below a predeterminedset point. In this manner, when the actual temperature is very near thelimit temperature, the method 510 goes into a fault-type condition anduses a safe duty cycle.

[0294] Assuming the actual plate temperatures are below the safetemperature limit, the method 510 applies the combined heater duty cyclefrom the parallel control algorithms at summation point 544. The heaterduty cycle applies full power for a certain percentage of a given amountof time. The given amount of time is the update speed of the fuzzy logiccontrol loop. The fuzzy logic control loop, including the fuzzy logiccontrol algorithm 530, updates about nine times per second in onepreferred embodiment. It should be appreciated that the update rate ofthe fuzzy logic control loop is an important parameter and that simplyincreasing the update rate to a certain value may deteriorate theaccuracy of the system. One range of update rates that provide goodresults is from about 8.5 times per second to about 9.5 times persecond.

[0295] The update rate should not be evenly divisible into the frequencyof the input power. For example, an update rate of nine times per secondworks when the AC frequency is held steady at 50 or 60 hertz. However,as is the case in some countries, the frequency may be 63 hertz. In sucha case, an update rate of nine hertz will cause inaccuracy. Therefore,in one preferred embodiment, an update rate of a fraction of 1 hertz ispreferred, such as 9.1 hertz. Assuming the update rate to be nine timesper second, the time per update is approximately 110 milliseconds.Therefore, if the duty cycle is 0.5, i.e., half on, half off, the timeat which full power is applied is 55 milliseconds. During the other 55milliseconds, no power is applied. If the duty cycle is 90%, then fallpower is applied for 90% of 110 milliseconds.

[0296] The update speed of the knowledge-based control algorithm 520 isnot as critical as the update speed of the fuzzy logic control loop. Forone reason, the signal inputs to the algorithm 520 change gradually overtime so that they do not need to be checked as often as the comparisonbetween the desired fluid temperature and the actual fluid temperature.An update rate of about two seconds is sufficient for the signal inputs.The inputs of the control algorithm 520 can be updated from about onceevery half second to about once every four seconds. The knowledge-basedcontrol algorithm 520 can run on the main processor of the system 10,100, for example, an Intel StrongARM® Processor. To facilitate theupdate rate of the fuzzy logic control loop, a high speed processor,such as a Motorola Digital Signal Processor is used. The fuzzylogic-based control algorithm 530 runs, in one embodiment, on a delegateprocessor, e.g., a Motorola Digital Processor.

[0297] Referring now to FIG. 26, the knowledge-based control algorithm520 is illustrated in more detail. As discussed above, in a first step,the knowledge-based control algorithm receives a number of signalinputs, as indicated by block 522. Some of these inputs are updated atthe main processor level of about once every two seconds. Other inputsare set in software as constants. One of the input signals that variesover time, is the number of stroke intervals (“N”) per millisecond. Thepump piston moves over a certain period of time, stops and dwells, andthen moves again for a certain period of time. The pump makes N numberof strokes per millisecond, which is inputted into the knowledge-basedcontrol algorithm.

[0298] Another input signal that varies over time is the input voltage(“V_(ac)”). The input voltage V_(ac) changes over time in a single houseor in different locations. Another input signal that changes over timeis the measured fluid inlet temperature (“T_(in)”). Fluid temperatureT_(in) is measured by one of the numerous sensors of the method 510described above. An input which will like not change over time is theplate heater efficiency (“E”). The heater efficiency E is determinedempirically. The heater efficiency E could change depending upon thepressure inside the disposable unit during heating, the material of thedisposable unit and the gap tolerance between the top and bottom plate.The heater efficiency E for a particular dialysis device thereforeremains substantially constant. As described above, the desired fluidtemperature (“T_(desired)”) may vary, depending on doctor's orders.However, for any given therapy session, T_(desired) is a constant.

[0299] The knowledge-based control algorithm 520 calculates a pulsatileflowrate (“Q”) in millimeters per minute according to the formula ofblock 524. The formula for Q can change based on the desired units forthe flowrate. In the illustrated embodiment, the formula for Q is 60,000multiplied by the chamber volume in milliliters, the product of which isdivided by T in milliseconds. Once again, the chamber volume is aconstant that is a function of pump chamber wall geometry.

[0300] The knowledge-based control algorithm 520 also calculates thetotal heater power in Watts, as indicated by block 526. In theillustrated embodiment, the method 510 calculates the heater power bydividing V_(ac) ² by a plate heater resistance. The knowledge-basedcontrol algorithm 520 then uses the above calculations to calculate theknowledge-based duty cycle, as indicated by block 528. Theknowledge-based duty cycle equals, in one embodiment, a factor, e.g., of0.07, multiplied ΔT, which equals T_(desired) minus the T_(in) Thisproduct is then multiplied by the pulsatile flowrate Q. The latterproduct is then divided by the product of the total heater power W timesthe heater efficiency E. The knowledge-based duty cycle is then fed intosummation point 544 in combination with the fuzzy logic-based duty cycleoutput as illustrated by FIG. 26.

[0301] Referring now to FIG. 27, one embodiment for the fuzzy logiccontrol algorithm 530 is illustrated. It should be appreciated thatfuzzy logic is known generally to systems engineers and in the field ofsystem and process control. The fuzzy logic algorithm described hereinis merely one method of implementing fuzzy logic to perform the task ofaccepting an error input, which is the difference between the desiredfluid temperature and the actual fluid temperature, and attempting tominimize this number to zero. Regardless of the method in which fuzzylogic is employed, the method inputs ΔT and outputs a power limiter,such as the duty cycle. The first step in the fuzzy logic control logicalgorithm 530 is to therefore calculate the difference betweenT_(desired) and T_(in), as indicated by block 532.

[0302] Next, a number of membership functions are implemented, asindicated by block 534. In this embodiment, the algorithm 530 implementsfive measurement functions. Two of the measurement functions, namely,nlarge and plarge, are trapezoidal membership functions. As is known inthe art of fuzzy logic, the trapezoidal membership function consists offour nodes. Three other membership functions, namely nsmall, neutral andpsmall, are set up as triangle membership functions, which consists ofthree nodes. After setting up the membership functions as indicated byblock 534, the fuzzy logic control algorithm 530 performs afuzzification interface as indicated by block 536. In the fuzzificationinterface, the control algorithm 530 converts the temperature differenceΔT between T_(desired) and T_(in) to a number of fuzzy sets based on themembership functions set up as indicated in block 534.

[0303] Next, the control algorithm 530 applies a number of fuzzy logicheating rules as indicated by block 538. In an embodiment, the controlalgorithm 530 employs five fuzzy logic rules. One rules says that, if ΔTis nlarge, the output should decrease at a large pace. Another rulessays that, if ΔT is nsmall, the output should decrease at a small pace.The third rule states that if ΔT is neutral, the output should be zero.A further rules states that if ΔT is psmall, the output should increaseat a small pace. The final rule states that if ΔT is plarge, the outputshould increase at a large pace.

[0304] The next step in the fuzzy logic control algorithm 530 is toperform a defuzzification interface, as indicated by block 540. In thedefuzzification interface, the output of the rules is converted to anactual or “crisp” output, which can then be translated into a dutycycle. In the defuzzification step indicated by block 590, the output ofthe fuzzy logic rules is converted to a “crisp” or exact number. Thisnumber is then converted to the proper output for the heater which, inthis embodiment, is the fuzzy heater duty cycle.

[0305] As indicated by block 542, the next step is to determine how muchweight to place on the fuzzy logic duty cycle with respect to theknowledge-based duty cycle. The weighting factor is decided by the fuzzylogic rules and the update rates of both the knowledge based and fuzzylogic based control algorithms. The weighted fuzzy logic duty cycle isthen summed in summation point 544 with the knowledge-based duty cycleyielded by the knowledge-based control algorithm 520.

IX. Electrical Insulation for the System

[0306] Medical equipment and in particular equipment in intimate contactwith a patient needs to be properly electrically insulated againstleakage currents. Class I type of equipment provides basic insulationand a means of connecting to a protective earthing conductor in thebuilding in which the equipment resides, which dissipates hazardousvoltages if the equipment insulation fails. One primary use for thesystem 10, 100 of the present invention however is in a patient's home.This presents two problems for Class I devices and in particular fordialysis machines. First, in many countries and older homes, theearthing ground is faulty, unreliable or completely absent. Second, manypeople bypass grounding systems that do exist. The present inventionovercomes this problem by providing an automated dialysis system 10, 100that requires no earth ground. The system 10, 100 does not simply relyon the basic insulation provided by Class I devices but provides eitherdouble insulation or reinforced insulation.

[0307] Double insulation includes two layers of insulation. One layer ofinsulation can be the basic insulation. At 240 VAC, basic insulationtypically requires four millimeters of “creepage” or 2.5 millimeters of“air clearance”. Creepage is the shortest distance between twoconductive parts when both are disposed along a surface of insulation.Creepage is also the shortest distance between a conductive part and abounding surface of a piece of equipment, wherein the conductive partand the equipment contact a piece of insulation. Air clearance is theshortest distance between two conductive parts or between a conductivepart and a piece of equipment, measured through air.

[0308] The additional layer of insulation is called supplementalinsulation. Supplemental insulation is independent insulation applied inaddition to the basic insulation to ensure protection against electricshock if the basic insulation fails. The supplemental insulation canalso be in the form of creepage and clearance.

[0309] Reinforced insulation, on the other hand, is a single layer ofinsulation offering the same degree of protection as double insulation.Reinforced insulation provides the electrical protection equivalent todouble insulation for the rated voltage of the double insulation. For240 VAC, used as the mains voltage of the system 10, 100, the basicinsulation can withstand 1500 VAC and the supplemental insulation canwithstand 2500 VAC. The single layer of reinforced insulation musttherefore withstand at least 4000 VAC.

[0310] Referring now to FIG. 28, one embodiment of an electricallyinsulated system 550 of the present invention is illustrated. The system550 is illustrated schematically, however, certain components of thesystem 550 are identifiable as components illustrated in the hardwaredrawings discussed above. For example, the system 550 includes thehousing or enclosure 112, illustrated above in FIGS. 3A to 4B, whichincludes the base 114 and the lid 116 of the hardware unit 110. Thesystem 550 also includes the heater 16, which in an embodiment includesupper and lower heating plates illustrated in FIG. 3A and discussed inconnection with FIGS. 25 to 27. Further, the system 550 includes thedisplay device 40 and temperature sensors 62 illustrated and discussedin connection with FIGS. 1 and 2.

[0311] In FIG. 28, the numbers in parenthesis indicate the working oroperating voltage of the respective component. As illustrated, the line552 and neutral 554 supply a mains voltage of 240 VAC, single phase, inan embodiment, which is the standard voltage used residentially in manycountries throughout the world. The line 552 and neutral 554 couldotherwise supply the United States residential standard of 120 VAC,single phase, and indeed could provide a voltage anywhere in the rangeof 90 to 260 VAC. The line 552 and neutral 554 feed the 240 VAC into amains part 556. It is worth noting that the system 550 does not includeor provide a protective earth conductor.

[0312] The mains part 556 feeds 240 VAC to a power supply printedcircuit board (“PCB”) 558. Power supply PCB 558 includes a mains part562 and a live part 564. For purposes of the present invention, a “mainspart” is the entirety of all parts of a piece of equipment intended tohave a conductive connection with the supply mains voltage. A “livepart” is any part that if a connection is made to the part, the part cancause a current exceeding the allowable leakage current for the partconcerned to flow from that part to earth or from that part to anaccessible part of the same equipment.

[0313] As illustrated, the live parts 560 and 564 step down in voltagefrom the mains parts 556 and 562, respectively, to 24 VDC. Obviously,the voltage may be stepped down to other desired levels. Live part 560feeds live part 566. Live part 566 is an inverter having a step-uptransformer that outputs a voltage of 1200 V_(peak). The inverter 566powers a number of cathode fluorescent lights, which providebacklighting for the display device 40.

[0314] Live part 560 is also electrically isolated from applied part568, which is maintained at a zero potential. An “applied part” forpurposes of the present invention is any part of the system 550 that:(i) comes into physical contact with the patient or operator performingthe dialysis treatment; (ii) can be brought into contact with thepatient or operator; or (iii) needs to be touched by the patient. Forinstance, it is possible for the patient to touch the upper or lowerplates of the plate heater 16, the temperature sensors 62 and theenclosure or housing 112. The applied part 568 represents schematicallythe casing or insulation around the temperature sensors 62.

[0315] In an embodiment, which only includes a display device 40 and nota touch screen 42 (discussed in FIGS. 1 and 2), the housing 112 includesa window 570, such as a glass or clear plastic window. The glass orplastic window provides the same level of insulation as the rest of the,e.g., plastic housing or enclosure 112. In an embodiment which doesinclude a touch screen 42, the touch screen is properly electricallyinsulated, preferably by the manufacturer of same. Alternatively, one ormore layers of insulation discussed below could be added to system 550to properly insulate the touch screen 42.

[0316] The system 550 makes available an input/output port 572, whichcan be a serial port or an Ethernet port to connect the system 550 to anexternal computer, a local area network, a wide area network, aninternet and the like. To electrically insulate input/output port 572,the system provides a protective covering or casing 574.

[0317] The mains part 556 powers the heater element 576, which ispositioned and arranged to heat both the upper and lower plates of theplate heater 16. In an alternative embodiment (not illustrated), themains part 556 powers the infrared heater discussed above. Asillustrated, double insulation is maintained between the heater element576 and the heater plate 16. The double insulation includes basicinsulation B(240), rated for 240 VAC, and supplemental insulationS(240), rated for 240 VAC.

[0318] For the heater plate 16 and element 576, at least, the basic andsupplemental insulation needs to be electrically insulative butthermally conductive. Polyimides, such as a Kaptong®, work very well. Inan embodiment, therefore, the B(240) and S(240) layers each includeKapton® tape or sheet of about 0.3 millimeters thickness. As furtherillustrated, another layer of basic insulation B(240), rated for 240VAC, and another layer of supplemental insulation S(240), rated for 240VAC, are disposed between the temperature sensor 62 and the heater plate16. Thus the heater plate 16 is completely and doubly insulated from theremainder of the system 550. Alternatively, either of the double layersof insulation can be replaced by a single layer of reinforcedinsulation.

[0319] The line 552 and the neutral 554 are insulated by basic operationinsulation BOP(240), rated for 240 VAC, which is the electricalinsulation wrapped or extruded around the respective wires. Basicinsulation B(240), rated for 240 VAC, is provided between the mains part556 and the enclosure 112 and between the power supply PCB 558 and theenclosure. The basic insulation B(240) can be in the form of a properlyseparated air gap. The enclosure 112 itself provides supplementalinsulation S(240) for 240 VAC. The mains part 556 is therefore doublyinsulated from the outside of the enclosure 112.

[0320] Since applied part 568 is maintained at a zero operating voltage,there needs to be no additional insulation placed between the appliedpart 568 and the housing 112. Accordingly, there is simply anoperational separation displayed figuratively as OP between the appliedpart 568 and the housing 112. Double insulation or reinforced insulationD/R (24) for 24 VDC is however provided between live part 560 and theapplied part 568, so that applied part 568 maintains its zero potential.Basic insulation B(24), rated for 24 VDC, is provided between live part560 and the enclosure 112. The basic insulation B(24) can be in the formof a properly separated air gap. As stated above, the enclosure 112itself provides supplemental insulation S(240) for 240 VAC. Live part560 is therefore doubly insulated from the outside of the enclosure 112.

[0321] No additional insulation is needed and only an operationalseparation OP is provided between live part 560 and the live part 566.Since live part 566 is stepped up to 1200 V_(peak), the supplementalinsulation S(240) rated for only 240 VAC of the enclosure 112 should notbe relied upon. Accordingly, double insulation or reinforced insulationD/R (1200) for 1200 V_(peak) is provided between the live part 566 andthe housing 112.

[0322] Double insulation or reinforced insulation D/R (240) for 240 VACis provided between the mains part 556 and the live part 560. Doubleinsulation or reinforced insulation D/R (240) for 240 VAC is alsoprovided between the line and neutral line 554 and the upper and lowerplates of plate heater 16. Still further, double insulation orreinforced insulation DIR (240) for 240 VAC is provided between themains part 562 and the live part 564 of the power supply PCB 558. Here,in the case of double insulation, either the basic or supplementaryinsulation can be a properly separated creepage distance on the PCB 558.

[0323] Double insulation or reinforced insulation D/R (24) for 24 VDC isprovided between the housing 112 and the display device 40. Theseparation between the display device 40, maintained at 24 VDC and theinverter, maintained at 1200 V_(peak) is only required to beoperational. Live part 566 must be separated from the outside of thehousing 112 by D/R(1200) but not from the LP(24). The reason is that theLP(1200) is on the secondary side of the live part 566 and if it isshorted to the LP(24) due to a failure of the operational insulation,LP(1200) will become at most 24 VDC, providing no safety hazard.

X. Graphical User Interface

[0324] Referring now to FIG. 29, one embodiment of a graphical userinterface (“GUI”) system 600 is illustrated. The GUI system 600 in anembodiment employs web-based software as well as other types ofsoftware. As discussed previously in connection with FIG. 28, the system10, 100 of the present invention is provided with an input/output (e.g.,serial or Ethernet) port 572, which is normally insulated from thepatient by a cover 574. The port 572 allows the controller 30 of thesystem 10, 100 to access an internet and a variety of other networks.The GUI system 600 of the present invention takes advantage of thiscapability by enabling the controller 30 to interact with software on aninternet or other network.

[0325] It should be appreciated that the GUI system 600 does not requirethe patient to have internet or network access in their home. Rather,the port 572 is for a maintenance person or installer to gain access tothe controller 30 within the hardware unit 110. In this manner, thepatient may bring their unit to a place having internet or networkaccess, wherein the patient's software may be upgraded. The patient maythen bring the unit home and operate it without having to gain internetor network access.

[0326] Using web-based software is advantageous because it is based onwell established standards, so that the interface screens may beconstructed using existing software components as opposed to being handcrafted. Web-based software allows for external communication andmultiple access points. The software is portable. For each of thesereasons, software constructed using existing software components reducesdevelopment time and cost.

[0327] The present invention includes the construction of a GUI using anembedded web browser 602. In an embodiment, the embedded web browser 602is third party software. The embedded web browser 602 can include anythird party browser that runs on a target platform and includes supportfor advanced features such as HTML 4.0, ECMAScript, and animated GIFs.The web browser 602 renders and supplies the various GUI screens to thevideo monitor 40. The web browser 602 also handles inputs made by thepatient. When the operator interacts with the system (e.g., pressesbuttons 43, 124, 125 and 127 or turns knob 122, illustrated in FIG. 3B),the web browser 602 forwards information about the interaction to theembedded web server 604.

[0328] The web server 604 in turn uses a web server extension software606 to process the interaction. The embedded web server 604 can also beany third party web server that runs on a target platform and includessupport for the web server extension software 606 and that allows adynamic definition of the information to be sent to the embedded webbrowser 602.

[0329] The web server extensions are developed internally using the webserver extension software 606 and conform to the specification of amechanism, such as a Servlet, which works in conjunction with the chosenembedded web server 604. The web server extension software 606 enablesthe web server 604 to retrieve back end and real time information fromthe instrument access and control software 608. There are a number ofdifferent existing web server extension technologies that may be usedfor the embedded web browser 602, the embedded web server 604 and theweb server extension software 606, such as CGI, ASP, Servlets or JavaServer Pages (“JSP”).

[0330] The web server extension software 606 interacts with theinstrument access and control software 608. The instrument access andcontrol software 608 is an internally developed operating environmentfor controlling the various lower level components of the system 10,100, such as the valve motor/actuator, pump motor/actuator and heater.

[0331] Depending on the operator input and the state of the automateddialysis system 10, 100, the web server extension software 606 caninteract with the instrument access and control software 608 to obtaininformation from same and to cause one of the devices of the system 10,100 to take action. The web server extension software 606 then sendsinformation to the embedded web browser 602, which may then be displayedon the display device 40. The web server extension software 606communicates with the instrument access and control software 608 using,in an embodiment, the CORBA standard. This communication, however, maytake place using various different protocols known to those of skill inthe art.

[0332] During the operation of the system 10, 100, an event may occurthat requires high priority information to be displayed to the operator,for example, an alarm and corresponding message either on the displaydevice 40 or on a separate dedicated alarm display. When a high priorityevent occurs, the instrument access and control software 608 generatesan event that is handled by an event-handling software 610, which can bedeveloped internally. The event-handing software 610 in turn notifiesthe embedded web browser 602, through the use of a plug-in or a refreshrequest simulation from the web server 604, to refresh whatever displaythe web browser is currently causing to be displayed on display device40.

[0333] The event-handing software 610 enables information to flow fromthe instrument access and control software 608 to the embedded webbrowser 602 without a request by the embedded web browser 602, whereinthe web browser thereafter requests a refresh. The web server 604 thenforwards the request to the web server extension software 606. The webserver extension software 606 determines what information should bedisplayed on the display device 40 based on the state of the system 10,110. The web server extension software 606 then relays that informationback to the embedded web browser 602, which updates the display device,e.g., to show an alarm condition.

[0334] In one embodiment of the GUI system 600, the web client isinternal to the hardware unit 110 of the system 10, 100. As describedabove in connection with FIG. 1, the controller 10 includes a pluralityof processors (referred to collectively herein as processor 34). A mainmicroprocessor is provided that resides over a number of delegateprocessors. Each of the embedded web browser 602, web server 604, webserver extension software 606 and event handling software 610 run on themain microprocessor. The instrument access and control software 608 runson the main microprocessor and one or more of the delegate processors.

[0335] It is alternatively possible that a number of different externalweb clients may need to access information contained within the system10, 100. It is therefore preferred that the HTTP commands to theembedded web server 604 not require predetermined passwords, but insteaduse a stronger and more flexible security system.

[0336] Referring now to FIGS. 30A-30M, a number of screen shots of theGUI 600 are illustrated that show the overall look and feel of thesystem 10, 100 as seen by the operator or patient. Further, thesedrawings illustrate various features provided by the GUI system 600. Thegoal of the automated dialysis system of the present invention is tomake a simple and well operating system. The device only requires twosupply bags 14, weighs less than 10 kg and can be powered virtuallyanywhere in the world without the risk of electrical shock to thepatient. Similarly, the GUI system 600 is designed to be simple,intuitive, effective, repeatable and reliable.

[0337] As illustrated in FIG. 3B, the system 10, 100 includes a displaydevice 40, a knob 122 that enables the user to interact with the GUIsystem 600 and a number of dedicated pushbuttons 43 that enable thepatient to navigate between three different screens namely a parameterchange screen, a log screen and a therapy screen. In an embodiment, adisplay device 40 is provided, wherein the input devices 43, 122, 124,125 and 127 are each electromechanical. In an alternative embodiment,one or more of the input devices are provided by a touch screen 42 thatoperates with the display device 40 and a video controller 38.

[0338] A simulated or electromechanical “stop” input 124, an “OK” button125 and a “back” button 127 are also provided. The OK button 125 enablesthe operator to indicate that a particular part of the set-up procedurehas been completed and to prompt the GUI 600 to move on to a next stepof the set-up stage or to the therapy stage. The stop button 124 enablesthe operator or patient to stop the set-up or therapy procedures. Thesystem 600 may include a handshake type of response, such as “are yousure you want to stop the set-up”. Other parts of the entire procedure,such as the patient fill or drain cycles immediately stop withoutfurther input from the operator. At certain points in the procedure, thesystem enables the operator to move back one or more screens using theback button 127.

[0339] Referring now to FIG. 30A, the display device 40 and the videocontroller 38 are adaptable to display animations, which provide thepatient with information and instructions 612 in a comfortable format.As illustrated throughout the screen shots, the GUI system 600 waits forthe patient to read and understand whatever is being displayed on thedisplay device 40 before moving on to the next step or stage. FIG. 30Aillustrates that the GUI system 600 is waiting until the patient isready before beginning the therapy. The system 600 prompts the user topress an “OK” input to begin the therapy. FIG. 30A also illustrates thatthe therapy screen is being presently displayed by highlighting the word“therapy” at 614.

[0340] In FIG. 30B, the display device 40 of the GUI system 600 promptsthe patient to gather the necessary supplies for the therapy, such asthe supply bags 14. FIGS. 30B and 30C illustrate that the system 600uses static images, such as static image 616 and animations, such asanimation 618, which resemble the actual corresponding supplies or partsto aid the patient in easily, effectively and safely connecting to thesystem 10, 100. For example, the animation 618 of FIG. 30C looks likethe actual hose clamp of the system 10, 100, which aids the patient infinding the proper piece of equipment to proceed with the therapy. Thearrow of the animation 618 also illustrates the action that the patientis supposed to perform, reducing the risk that the patient willimproperly maneuver the clamp or perhaps break the clamp.

[0341]FIGS. 30D and 30E illustrate that the GUI system 600 promoteshygienic operation of the system 10, 100 by prompting the patient to:(i) take the steps of covering the patient's mouth and nose at theproper time; and (ii) wash the patient's hands before coming intocontact with critical fluid connectors, such as the patient fluidconnector and the supply bag connectors. The GUI system 600 waits forthe patient to finish and press an OK input at each step beforeproceeding to the next step. As illustrated in FIGS. 30D and 30E,software LEDs 620 located at the top of the display device 40 indicatewhere the user is in the setup procedure.

[0342] Screen shots of FIGS. 30A to 30E and 30H to 30M each presentprocedural set-up steps of the therapy. Accordingly, the colors of thescreen shots of FIGS. 30A to 30E and 30H to 30M are chosen so that theyare more visible when viewed during the day or with lights on. In oneembodiment, the screens are different shades of blue, wherein the staticimages and animations and inner lettering are white and the outerlettering and borders are black. As illustrated by FIGS. 30F and 30Ghowever, the screen shots that illustrate the active stages of thetherapy are chosen so that they are more visible when viewed at night orwith lights off. In one embodiment, the screen shots of FIGS. 30A to 30Fare black with ruby red lettering, diagrams and illustrations, etc. Thered letting is configured so as not to be intrusive to a sleepingpatient but still visible at distances of about 10 to 25 feet (3 to 7.6meters).

[0343]FIGS. 30F and 30G illustrate that during active stages of thetherapy, the therapy status information is displayed on the screen shotsin the form of both graphics 622 and numerical data 624. Therapy statusinformation is displayed in real time or in substantially real time witha slight time delay. FIG. 30F illustrates a screen shot during a fillportion of the therapy. In particular, FIG. 30F illustrates the firstfill of three total fills. The graphical clock 622 illustrates that thefill cycle time is approximately ⅛th elapsed. The arrow graphic 622indicates that the therapy is in a fill cycle. Also the graphicalrepresentation of the body 622 has a very low percentage of dialysate.The numerical data 624 illustrates that the system 10, 100 has pumped150 ml of dialysate into the patient.

[0344]FIG. 3G illustrates that the patient is currently undergoing thefirst drain cycle of three drain cycles that will take place overnight.The graphical representation of the clock illustrates that the draincycle time is approximately ⅛th elapsed. The graphical arrow is pointingdownward indicating a drain cycle. The body is shown as beingsubstantially full of dialysate. The numerical data 624 illustrates that50 ml of dialysate has been removed from the patient.

[0345]FIGS. 30H and 30I illustrate that in the morning when the therapyis complete, the screen reverts back to the daytime colors, or colorswhich are more easily seen in a lighted room. FIG. 30H includesinformation and instructions 612 that prompt the patient to disconnectfrom the system 10, 100. The system waits for the patient to select theOK button 125 (FIG. 3B) before proceeding. FIG. 30I includes ananimation 618, which illustrates an action and equipment that thepatient while disconnecting from the system. For each action in thedisconnection sequence, system 600 waits for the patient to select theOK button 125 (FIG. 3B) before proceeding.

[0346]FIGS. 30J to 30M illustrate that in an embodiment, the usernavigates between the therapy, parameter changes and log information byselecting one of the dedicated inputs 43 illustrated in FIG. 3B. FIG.30J illustrates that the patient has selected the input 43 associatedwith the parameter changes information. The screen 40 in FIG. 30J nowhighlights the word “changes” instead of the word “therapy.”

[0347] The parameter screen presents parameter information to thepatient in a hierarchy format. First, as in FIG. 30J, the system 600presents categories 625 of parameters, such as patient preferences,daily patient data, therapy parameters, nurse parameters and serviceparameters. The patient can scroll through the various categories 625using the adjustment knob 122 of FIG. 3B, so that a desired category 625is displayed in a highlighted display area 626. FIG. 30H illustratesthat the patient preferences category 625 is currently displayed in thehighlighted display area 626.

[0348] Once the user selects a highlighted category 625 by pressing theOK button 125 (FIG. 3B), a first door 628 slides open and presents theuser with a list of the parameters 627 for the selected category 625(e.g., the patient preferences category), as illustrated by the screen40 of FIG. 30K. FIG. 30K illustrates that the patient preferencescategory 625 is displayed above the door 628, so that the patient knowswhich category 625 of parameters 627 is being displayed. At the sametime, the highlighted display area 626 now displays one of a selectgroup of the parameters 627 belonging to the patient preferencescategory 625.

[0349] The parameters 627 illustrated in FIG. 30K as belonging to thepatient preferences category 625 include a display brightness percent, aspeaker volume percent and a dialysate temperature in degree Celsius.Obviously, the patient preferences category 625 may include otherparameters 627. The other categories 625 illustrated in FIG. 30J includedifferent parameters 627 than those illustrated in FIG. 30K.

[0350] The patient can scroll through and select one of the parameters627 for the patient preferences category 625 by rotating knob 122. Inthis manner, it should be appreciated that the signal knob 122 is usedover and over again. This feature is in accordance with the goal ofproviding a simple system, wherein the patient only has to turn one knobinstead of remembering which knob from a plurality of knobs applies to aparticular feature. The knob 122 also enables the lettering to be biggerbecause the patient can scroll through to see additional parameterselections that are not displayed when the door 628 is initiallydisplayed. That is, the functionality of the knob 122 provides freedomto the GUI 600 to not have to display all the possible parameters atonce. It should be appreciated that this benefit also applies to thecategory selection screen of FIG. 30J, wherein each of the categories625 does not have to be displayed simultaneously.

[0351] Once the patient selects one of the parameters of the patientpreferences category, e.g., by pressing the OK button 125, a second door630 slides open, wherein the display device 40 illustrates that thepatient has selected the display brightness parameter 627 of the patientpreferences category 625, which is still displayed by the first door 628in FIG. 30L. The highlighted area 626 now displays one of the range ofpossible values 632 for the selected parameter 627 of the selectedcategory.

[0352] In FIG. 30L display device 40 illustrates that the highlighteddisplay area 626 currently shows a value 632 of eighty for the displaybrightness parameter 627 of the patient preferences category. Onceagain, the patient changes the value 632 of the selected parameter 627by rotating the knob 122. When the patient selects a value 632 (bypressing the OK input 125 illustrated in FIG. 3B while the desired valueis displayed) for the parameter of the chosen category, the GUI system600 saves the value as indicated by the display device 40 in FIG. 30M.FIG. 30M illustrates that the system 600 provides a feedback message tothe patient that the selected value has been saved.

[0353] The system 600 in an embodiment presents information andinstructions to the operator through the various visual tools discussedabove. In an alternative embodiment, in addition to the visualinformation and instructions 612, static images 616, animations 618,parameter information, etc., one, or more or all of the above disclosedmethods of communication is presented audibly to the patient or operatorthrough speakers 129 (FIG. 3B) and a sound card (not illustrated) thatcooperate with the controller 30 of the system 10, 100.

[0354] The various programs that run on the main microprocessor can alsoinclude one or more programs that activate a certain sound file at acertain time during the therapy or upon a certain event initiated by thesystem 600, e.g., an alarm, or upon a patient or operator input. Thesound files can contain the sound of a human voice or any other type ofsound. The sound files walk the patient through the set-up portion ofthe therapy in an embodiment. The sound files can alert a patient whohas made an inappropriate input into the GUI 600, etc. The system doesnot activate a sound during the cycles, e.g., while the patient sleeps,in a preferred embodiment.

[0355] If the operator selects the dedicated input 43 corresponding tothe log information (not illustrated), the GUI 600 displays a screen orscreens that show therapy data. In an embodiment, the therapy data ispresented in a number of operator selectable logs. One of the logs canbe a default log that is displayed initially, wherein the operator canswitch to another log via, e.g., the knob 122. The logs may pertain tothe most recent therapy and/or can store data over a number of days anda number of therapies. The logs can store any type of operatingparameter information such as cycle times, number of cycles, fluidvolume delivered, fluid temperature information, fluid pressureinformation, concentration of dialysate constituents, any unusual oralarm type of events, etc.

[0356] It should be understood that various changes and modifications tothe presently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present invention andwithout diminishing its intended advantages. It is therefore intendedthat such changes and modifications be covered by the appended claims.

The invention is claimed as follows:
 1. A method of controlling pressurein a medical fluid pump comprising the steps of: controlling a pumpmember acceleration during a first portion of a pump stroke; andadaptively changing the pump member velocity during a second portion ofthe pump stroke.
 2. The method of claim 1, which further includes thestep of controlling a pump member deceleration during the first portionof the stroke.
 3. The method of claim 1, wherein the pump stroke is apatient fill stroke.
 4. The method of claim 1, wherein controlling thepump member acceleration includes moving the member at a rate ofacceleration until a predefined velocity is reached.
 5. The method ofclaim 1, which includes the step of beginning the pump stroke at aninitial, non-zero velocity.
 6. The method of claim 1, which includes thestep of dividing the second portion into at least two sub-portions andadaptively changing the pump member velocity differently for thedifferent sub-portions.
 7. The method of claim 1, which includes thestep of adaptively changing the pump member velocity to correct forovershooting a pressure set point.
 8. The method of claim 1, whichincludes the step of adaptively changing the pump member velocity toachieve a pressure set point.
 9. The method of claim 1, which includesthe step of adaptively changing the pump member velocity to achieve adesired end of stroke velocity.
 10. The method of claim 1, whereinadaptively changing the pump member velocity includes determining anerror between a desired pressure and an actual pressure and performingan error compensating for the determined error.
 11. The method of claim10, which includes the step of storing the error compensation for use ina subsequent pump stroke.
 12. The method of claim 10, which includes thestep of adjusting the error compensation during a subsequent stroke. 13.The method of claim 10, which includes the step of adjusting the errorcompensation during a subsequent stroke based on an error determinationmade during the subsequent stroke.
 14. The method of claim 1, whereinadaptively changing the pump member velocity includes changing thevelocity based on at least one parameter selected from the groupconsisting of: a beginning pump member acceleration, a pressureproximity threshold, a rate of pressure change, a maximum pump membervelocity, a pump member deceleration, a proportional coefficient, aderivative coefficient and an integral coefficient.
 15. The method ofclaim 14, which includes changing the velocity based on different onesof the parameters during different sub-portions of the second portion ofthe stroke.
 16. A method of controlling pressure in a medical fluid pumpcomprising the steps of: effecting a pump member acceleration anddeceleration during a first portion of a pump stroke, the accelerationand deceleration determined before the first portion; using a first setof factors determined during a second portion of the pump stroke tochange the pump member velocity during the second portion; and using asecond set of factors determined during a third portion of the pumpstroke to change the pump member velocity during the third portion. 17.The method of claim 16, wherein the first set of parameters corrects anovershoot or undershoot in actual pressure with respect to a desiredpressure caused during the first portion of the pump stroke.
 18. Themethod of claim 16, wherein the second set of parameters causes anactual pressure to oscillate about a desired pressure.
 19. The method ofclaim 16, wherein the pump stroke is a first pump stroke and whichincludes bypassing the acceleration/deceleration of the first portion ofthe first stroke, and using only the adaptive control of the second andthird portions of the first stroke, during all of a second pump stroke.20. The method of claim 16, which includes adapting at least one of thefirst and second sets of parameters to compensate for a system variableselected from the group consisting of: patient physiology, fluid supplyelevation, fluid supply level and fluid drain level.
 21. A method ofcontrolling pressure in a medical fluid pump comprising the steps of:adaptively controlling fluid pressure in a first patient fill stroke;remembering at least one parameter setting used for changing thepressure in the first patient fill stroke; and adaptively controllingfluid pressure in a second patient fill stroke using the parametersetting used during the first patient fill stroke.
 22. The method ofclaim 21, which includes the step of adjusting the parameter setting foruse during the second patient fill stroke.
 23. The method of claim 22,which includes the step of deciding whether to adjust the parametersetting based upon whether an error between actual pressure and adesired pressure has increased or decreased.
 24. The method of claim 21,wherein adaptively controlling the first and second patient fill strokesincludes controlling the velocity of a motor.
 25. The method of claim21, which includes adaptively controlling a plurality of patient fillstrokes, storing the parameter setting in a data table and modifying thesetting over the plurality of strokes.
 26. A method of controllingpressure in a medical fluid pump comprising the steps of: controllingfluid pressure in a fluid pump fill stroke using pure adaptive control;and controlling fluid pressure in a patient fill stroke using a presetmotion control and adaptive motion control.
 27. The method of claim 26,which further includes the step of: controlling fluid pressure in apatient drain stroke using pure adaptive control; and controlling fluidpressure in a drain stroke using a preset motion control and adaptivemotion control.
 28. An automated medical fluid system comprising: amedical fluid pump; and a controller that operates with the medicalfluid pump to: effect a pump member acceleration during a first portionof a pump stroke, the acceleration determined before the first portion;use a first set of factors determined during a second portion of thepump stroke to change the pump member velocity during the secondportion; and use a second set of factors determined during a thirdportion of the pump stroke to change the pump member velocity during thethird portion.